Automotive Service Technician (AST)

2012 Guide - Second Period Package (36 Modules) Comments

Date: 9/22/2025 2:44:21 PM
Module: 090201a_2012
Version: 090204bB 2025 copy
Page: 28/30
Comment: Self test question 11 should be answered with C)Closerto the heel, except in the book the answer says D)Closer to the toe
Status: Approved for Review

Date: 1/5/2026 10:43:08 AM
Module: 090201aA
Version: 1st Edition
Page: 6
Comment: Module states Compression-Ignited Fuels Diesel fuel is the most common compression-ignited fuel. A side view of a direct injection spark ignition diesel motor is pictured in Figure 5. Diesel fuel is the most common compression-ignited fuel. An alternative compression-ignited fuel is biodiesel, a renewable fuel derived from biological sources like vegetable oils, animal fats, or recycled greases. The picture this refers to seems to be missing the spark plugs - Maybe the reason for this is that this A "direct injection spark ignition diesel motor" is a contradiction in terms, as diesel engines use compression ignition (no spark plug), while spark ignition (SI) engines use spark plugs and gasoline; This needs to be reviewed - and if you can show me a spark ignition diesel engine I would be grateful for the reference material - Maybe AI can great a picture of one????
Status: Approved for Review

Date: 1/5/2026 1:29:53 PM
Module: 090201aA
Version: 1st Edition
Page: 15 vs 17
Comment: On page 15 the ILM states "Diesel engines have very high compression ratios, typically ranging from 15:1 to 27:1." The on page 17 the ILM states Diesel engine compresses air to Approximately 18:1 Also on page 17 the ILM states Compression ratio is " 14:1 to 23:1" May I suggest you pick ONE ---- as having 3 answers within the same ILM is somewhat confusing It seems as if different sources were used (possibly by different people editing) Looking at the previous version of the ILM it has 15:1 to 27:1 - - Suggest you consider sticking with that Further note - Looking at Google AI - - it does list the 14:1 to 23:1 so this makes me wonder if some of the ILM was written with the help of AI ?? AI is a wonderful tool - - but suggest final proof reading is required by humans that will spend the time to research and verify. It is also possible that times and information changes and the "old answer" is outdated - - but the ILM needs to be consistent As stated - pick ONE answer
Status: Approved for Review

Date: 1/5/2026 3:39:58 PM
Module: 090201aA
Version: 1st Edition
Page: 53
Comment: Cast iron parts are baked at 260 °C (500 °F) for 5 to 6 hours; aluminum parts at 200 °C (400 °F) ---------------------------------- For accuracy - 200 C = 392 F - - Not 400
Status: Approved for Review

Date: 1/6/2026 1:51:21 PM
Module: 090201aA
Version: 1st Edition
Page: 36
Comment: Some manufacturers use displacement per cylinder to describe engine size, especially on large engines. For example: the GM Electro-Motive Division (EMD) 645 locomotive engine = 645 cubic inches per cylinder displacement. ------------------------------------------------------------------------------- Really? Honest question - who cares? ------------------------------------------------------------------------------- This is an Automotive Technician Course - - I have been in the industry for 50 years (1975-2025) and have never had one of these drive in for repair and I have worked on a lot of non-automotive engines from chainsaws to Frac Pumpers. Yes, I like trivia and learning more than "just" my area of the trade. But this has no real value to an automotive technician and should be removed
Status: Approved for Review

Date: 1/6/2026 2:13:38 PM
Module: 090201aA
Version: 1st Edition
Page: 38
Comment: There are some engines that exist in the modern automotive industry that do not even have a camshaft, but they will not be explored in this module. ___________________________________ A/ Why bring it up if it will not be explored B/ Please email me with an example of any "modern automotive example" - - I am aware of the "Freevalve engine" in the Koenigsegg Gemera - But I challenge you to provide an example of a production car or light truck using this technology that a journeyperson Automotive Tech will encounter. This is fluff and not required in the course.
Status: Approved for Review

Date: 1/6/2026 2:35:11 PM
Module: 090201aA
Version: 1st Edition
Page: 46
Comment: Single fuel engines and fuel systems are designed to operate with only one type of fuel (such as diesel, gasoline, methanol, propane, or natural gas). _-------------------------------------------------------------------- Happy to learn new things even at my age - Methanol engine? While it may be worth a classroom discussion (doubtful) I feel it is more important to teach what the techs will actually work on. I would suggest the reference be removed from the course ----------- methanol engines are extremely rare in the North American automotive market. Most methanol engine development has been concentrated in China and marine applications globally, not in mainstream North American cars or trucks. Here’s why: Infrastructure & Fuel Availability: North America lacks methanol fueling networks, making it impractical for consumer vehicles. Regulatory & Market Focus: The region prioritizes gasoline, diesel, and increasingly EVs and hydrogen rather than methanol. Use Cases: Methanol is mostly explored for marine engines, industrial generators, and some experimental racing engines—not for everyday passenger vehicles here. So, for an automotive journeyman course in Canada, methanol engines are not typically included because: They’re not part of standard OEM offerings in North America. Journeymen training focuses on systems they’ll encounter in dealerships and repair shops (gasoline, diesel, hybrids, EVs).
Status: Approved for Review

Date: 1/6/2026 2:40:30 PM
Module: 090201aA
Version: 1st Edition
Page: 8 and 46
Comment: Page 8 ------------------ A higher octane rating also makes it desirable to have more advanced ignition timing than with gasoline. Higher compression and more ignition advance result in better performance and economy. These modifications cannot be made if the engine is to be a dual fuel engine that will operate on gasoline part of the time. Like gasoline, LPG is also spark-ignited. -------------------- Page 46 ___________________ Engines can be classified by the fuel system(s) they operate on. There are single fuel and dual fuel engines available. • Single fuel engines and fuel systems are designed to operate with only one type of fuel (such as diesel, gasoline, methanol, propane, or natural gas). • Bi-fuel engines operate on either gasoline or propane. These operate separately on one fuel or the other, but not both at the same time. • Dual fuel engines and fuel systems are designed to operate with two types of fuel at once (for example, some engines are designed to run on a combination of diesel fuel and propane or natural gas). ------------------------- Issue - these pages contradict each other - page 8 says dual fuel where perhaps it should read BI-FUEL ?? Nitpicking ? Perhaps, but consistency is important in my opinion
Status: Approved for Review

Date: 9/10/2025 4:02:44 PM
Module: 090201aB
Version: 1st Edition
Page: 76
Comment: Please note that the question is in ILM 090201aB - But the question bank covers 090201aA and 090201aB - 3. The compression ratio of a diesel engine is high enough to cause the air being compressed to be heated to the: a) kindling point of the fuel. b) flash point of the fuel. c) fire point of the fuel. d) boiling point of the fuel. I have noticed that nowhere in the reference material do you use the term "Kindling" yet the correct answer is a) kindling point of the fuel Apparently the term was taught in previous versions. In My Opinion - if the answer uses a term - then the material should support this. Granted I am new to the college but have 50 years experience since I started in the trade - I would have picked the wrong answer based upon the material that was presented. Same set - different question 21. The purpose of the firewall on a liner is to: A. Protect the liner O-rings from excessive heat. B. Act as a combustion seal. *C. Reduce the heat and pressure acting on the head gasket. D. Prevent interference between the block and the liner. In this case the question asks the purpose of the "firewall" - But the term is not used in the material. - One more note The answer key shows 43 answers - but last question is 44 They fall out of sync because you do not have a question 35 - goes from 34 to 36 - this throws off the numbering in the answer key 34. When reconditioning a cylinder bore, you can use a deglazing hone to: a) Remove cylinder wall crosshatch. b) Remove cylinder bore taper. c) Remove cylinder bore out of round. d) Restore cylinder wall crosshatch. 36. The fasteners (cap screws, studs, nuts, washers) used on the exhaust system are often: a) Self-locking with nylon locking inserts. b) Left hand threaded fasteners. c) Retained with cotter pins. d) Heat treated and hardened.
Status: Approved for Review

Date: 1/6/2026 4:37:39 PM
Module: 090201aB
Version: 1st Edition
Page: 4
Comment: Machining material from the block deck surface also increases the compression ratio and advances valve timing on OHC (overhead cam) engines. This is consistent with what the old ILM states - but both are actually incorrect. Decking the block on an OHC engine will RETARD - not advance the timing ---------------------------------------------------------------------------- What “retard” vs “advance” means here Advanced cam timing: Intake opens/centerline occurs earlier (favors low–mid RPM torque). Retarded cam timing: Intake opens/centerline occurs later (often shifts power up the RPM range, but can hurt low-end). After decking, if you don’t correct cam phasing, you’ll typically see slight retard—which can subtly change drivability and emissions.
Status: Approved for Review

Date: 12/16/2025 3:39:29 PM
Module: 090201bA
Version: 1st Edition
Page: 58
Comment: ILM states "Engine stroke can be altered by building up one side of connecting rod journals and regrinding the journals back to the desired round size with a different journal offset. Some performance engine rebuilders use this method to build stroker engines." ------------------------------------------------------------------------ While offset grinding can technically be used to alter crankshaft stroke, it is a niche specialty process rarely used in modern engine rebuilding due to the availability of purpose-built stroker crankshafts. Inclusion as core instructional material may overemphasize a method most technicians will never encounter in practice. --------------------------- Just my thoughts - after 50 years in the trade I have never needed to know this -
Status: Approved for Review

Date: 1/7/2026 2:44:07 PM
Module: 090201bA
Version: 1st Edition
Page: 2
Comment: This individual learning module (ILM) content is presented in two booklets. ---------------------------------------------------------------- Suggest rewording to say THREE (3) as there is in fact 3 books • Internal Engine Components: Part A • Internal Engine Components: Part B • Internal Engine Components: Part C ------------------------------------------------------------ unless you are referring to Co-Requisites • 090201bB • 090201bC As the wording is directly following this --------------------------------------------------------- Feel the wording is misleading -
Status: Approved for Review

Date: 1/7/2026 2:57:28 PM
Module: 090201bA
Version: 1st Edition
Page: 2
Comment: The module also introduces friction bearings, explaining important terms like “crush” and “spread,” ----------------------------------- Please note that this statement is in all 3 booklets - 090201bA (p2), 090201bB (p3), and 090201bC (p2) --------------------------------- Looking through all 3 booklets it seems we lost a lot of information from the previous years... Booklet 090201c24 (2022) pages 17 through 27. To date we have not found this information in any of the booklets for second year. Suggesting this was omitted in error as it is alluded to in all 3 booklets
Status: Approved for Review

Date: 1/7/2026 4:30:07 PM
Module: 090201bA
Version: 1st Edition
Page: 51
Comment: ILM Cut and Paste ------------------------ Grinding or Machining Crankshafts Grinding crankshafts is an acceptable and satisfactory method of repair, providing that the undersize is not too great. As metal is ground off the crankshaft journals, the journals get smaller and are therefore reduced in strength. Under sizing of up to 1.0 mm (0.040 in.) is common, but in some exceptional cases may even exceed that amount. The most common repair grinds are as follows: • 0.025 mm (0.001in.), • 0.05 mm (0.002 in.), • 0.25 mm (0.010 in.), • 0.50 mm (0.020 in.), • 0.75 mm (0.030 in.), • 1.0 mm (0.040 in.), and • Undersized. ___________________________________________ Last line • Undersized. makes no sense as all the lines are "undersize" values Line should be removed
Status: Approved for Review

Date: 12/17/2025 9:27:07 AM
Module: 090201bB
Version: 1st Edition
Page: 11
Comment: Piston Crown Coating In today’s engines, manufacturers are using pistons with crowns coated with heat- resistant materials. In some applications, the piston head is coated with ceramic material and can withstand temperatures of 1093 ºC (2000 oF). --------------- Hard to defend "in todays engines manufacturers are using" - - - especially in Automotive - Suggest this was maybe intended for Heavy Duty??? Key Applications & Market Usage While most standard passenger vehicles use anodized or uncoated aluminum pistons, several specific production-adjacent examples use this technology: Heavy-Duty Diesel (Aftermarket & Specialized Build): Caterpillar (CAT) & Cummins: While not always a standard factory finish for every model, companies like PAI Industries and Industrial Injection produce "HP-2" and specialized ceramic-coated crowns for CAT 3406E, C15, and Cummins 5.9L/6.7L engines. These coatings are explicitly rated to withstand temperatures up to 2,000 °F (1,093 °C) and are marketed to prevent piston crown failure in "working" trucks under high boost or heavy towing. High-Performance "Crate" Engines: Ford Performance: Some high-end crate engines, such as specialized versions of the 5.0L Coyote or big-block 572 engines, use pistons with advanced coatings (often hard-anodized or ceramic-hybrid) to handle high-compression or turbocharged environments. Racing and Marine Applications: In the National Marine Manufacturers Association (NMMA) or NHRA racing, ceramic-coated pistons are considered standard for engines that endure sustained high-load, high-heat operation.
Status: Approved for Review

Date: 8/25/2025 11:00:55 AM
Module: 090201bC
Version: 1st Edition
Page: 30
Comment: What tool can be created to clean ring lands? The word "lands" should be replaced with "grooves"
Status: Approved for Review

Date: 1/19/2026 12:17:28 PM
Module: 090201c
Version: 1st Edition
Page: 65
Comment: Figure 67 shows a special micrometer for measuring valve stem height. - - - in fact it is not a special micrometer - - The figure caption has it correct stating - - - Figure 67 - Measuring valve stem height with a caliper. - - (and it does actually show a "Caliper")
Status: Approved for Review

Date: 1/19/2026 3:18:43 PM
Module: 090201dA
Version: 1st Edition
Page: 20
Comment: I seriously have to question page 20. You are picturing a Detroit Diesel Cylinder Head - Can you explain why this is a part of the automotive Service Tech ILM. This belongs in the Heavy Duty side. I had to do a bit of research to see if ANY automotive and light truck may use a split bearing shell for a camshaft. I did find a Ford 4.0 Liter 1997 - 2000 - But I feel that while it may be worth discussing this type of bearing - we need to concentrate on what we actually work on - Detroit Diesel does not seem to fit the bill....
Status: Approved for Review

Date: 1/16/2026 8:44:47 AM
Module: 090201dA
Version: 1st Edition
Page: 45
Comment: Your text - - - - - - If the camshaft fails to provide either one of its primary or secondary functions, it needs to be replaced, along with any affected connecting parts. A camshaft that still turns the power steering pump drive shaft but does not change rotating motion to linear reciprocating motion is not half working: it is fully malfunctioning. - - - Poorly worded ----- Couple suggestions for rewording If you’d like to keep it close to your original meaning (most direct): If the camshaft can no longer perform any of its required functions—primary or secondary—it must be replaced, along with any related components that may have been damaged. For example, a camshaft may still rotate and continue to drive an accessory such as a power steering pump, but if its lobes no longer produce the linear reciprocating motion needed to operate the valves, the camshaft has failed and the engine will not run correctly. If you want it shorter and punchier (good for training notes): If the camshaft cannot perform its valve-operating function, it is considered failed and must be replaced, along with any affected components. Even if it still turns and drives accessories, a camshaft that does not actuate the valves is not “partly working”—it is malfunctioning. If you want a more technical, cause-and-effect style: Any loss of camshaft function requires replacement of the camshaft and inspection or replacement of related parts. Although the shaft may continue to rotate and drive auxiliary components, correct engine operation depends on the cam lobes converting rotation into valve motion. If that conversion does not occur, valve timing is lost and the camshaft is functionally defective.
Status: Approved for Review

Date: 1/8/2026 2:05:44 PM
Module: 090201dB
Version: 1st Edition
Page: 9 and 10
Comment: Diesel Engine Two-Piece Piston - - ___________________________________ Why is this included in AST? This is heavy Duty information -----------------From ILM---------------------------- "Many diesel engine manufacturers (such as Detroit Diesel, Caterpillar, Mack and Cummins) use two-piece piston assemblies" ----------------------------------------------------- In my humble opinion I believe we do not need this information. Personally, I do appreciate knowing related information but this has no real value to an automotive service techs and just clutters up the module --------------------------------Additional info from the web--------------------- Examples of Engines Using Them (Historically & Currently): Detroit Diesel: Famous for their 2-stroke engines (like the 92 series), which often used crosshead or articulated piston designs for tough applications. Caterpillar: Uses two-piece articulated pistons in many heavy-duty engines, often recommending them for upgrades due to emission regulations. General Motors (GM): Some larger, older Detroit Diesel engines used by GM also featured two-piece pistons. Light-Duty Truck/Automobile Pistons: Modern Light-Duty Diesels (Cummins, Duramax, Power Stroke): Tend to use advanced one-piece pistons, often forged steel or high-strength aluminum with internal oil-cooling galleries, designed for strength in lighter packages. Light-Duty Two-Piece: While not common, some extreme performance or specialized aftermarket setups might use two-piece designs for extreme power, but stock light-duty pistons are typically one-piece.
Status: Approved for Review

Date: 10/30/2025 6:10:29 PM
Module: 090201i
Version: 2025
Page: 847,863,891
Comment: The text states that the major thrust side of the piston is the side contacting the cylinder wall on the power stroke, but the answer key for Activity One, Question Three, the answer key states it is the side of the piston contacting the cylinder wall on the compression stroke.
Status: Approved for Review

Date: 11/10/2025 12:58:10 PM
Module: 090201j
Version: 1st Edition
Page: 4
Comment: Oxygen cylinder Supplies pure oxygen (green tank in Canada) Acetylene cylinder Supplies acetylene fuel gas (red tank) Have to disagree with color of tanks all my sets the Acetylene tanks are black and the Oxygen are red(ish) Talking with the welding trade instructors - they suggest that there is no standard color and teach students to check labels
Status: Approved for Review

Date: 1/14/2026 9:02:13 AM
Module: 090202b
Version: 1st Edition
Page: 16
Comment: Figure 9 - exploded view of a clutch disc - - Marcel Springs with an arrow pointing to torsional springs - -
Status: Approved for Review

Date: 9/22/2025 2:38:19 PM
Module: 090204bB
Version: 2025 edition
Page: 21 and The Final Self Test
Comment: The picture on page 21 is of an axle seal NOT a pinion seal, The Self Test has question 2 as AABC as opposed to ABCD
Status: Approved for Review

Date: 11/6/2025 10:38:46 AM
Module: 090205b
Version: 1st Edition
Page: 39, 80
Comment: Page 39 Objective 4 Activity Question 3 3. When a vehicle is equipped with an additional generator that was installed by an aftermarket installer, what steps should be taken when diagnosing a charging system fault? a) Test the generators together as well as individually to confirm the source of the fault. b) Test the aftermarket generator and wiring first as it is more likely to have electrical faults than the factory charging system. c) Swap the factory generator and the aftermarket generator connections to see if the electrical fault also moves from one electrical system to the other. d) Disengage the aftermarket generator to test the factory charging system, advise the customer to return to the aftermarket installer if the factory charging system has no issues. Page 80 Correct answer 3. d) Disengage the aftermarket generator to test the factory charging system, advise the customer to return to the aftermarket installer if the factory charging system has no issues. I have an issue with this - A simple charging system that was added to a vehicle. In what world should a tech or shop admit defeat and send work out to the "aftermarket installer" A charging system should be basic knowledge. Yes there may be little to no documentation provided with the truck as customers typically do not supply it. But a tech should be able to figure out the system - Charging systems are basic knowledge. (and most systems that are aftermarket will have a website and tech support where information and diagrams can be accessed) I have worked in the trade with techs of all levels and not one of them would suggest throwing up your hands in defeat and sending work out of the shop for a charging system. Specialized tools and knowledge may be required for some work and a shop may not want to invest in specialized repairs, but a charging system is not one of those cases. We are training techs.... Not people that pass the work to someone else Perhaps some automotive transmission overhaul work that requires specialized tools Not an alternator that is not charging. Thanks
Status: Update in Progress


Archived Comments

Year: 2021

6/22/2021 11:46:42 AM
Module: 090201o
Version:
Page:
Comment: The calculation of the increase in boiling point of coolant due to an increase in pressure has some errors. The ILM states that 3.25F is 2C. This is not correct -one degree Celsius is 1.8 times larger than one degree Fahrenheit. This error shows up in the calculation as the final answer calculted in fahrenheit is 257.5F. 257.5F is actually 125.3C not 128C as is calculated using metric. Using 2C is equal to 3.6F, you calculate 212F + (14 *3.6F) = 262.4F. 262.4F is equal to 128C. Also the starting point for the calculation is given at 212F (100C) (the boiling point of water) not sure why that is used rather than 225F (107C) given for a 50/50 mix on pg 7. The calculation is the for the boiling point elevation of coolant, not water.
Status: Implemented

6/22/2021 11:11:06 AM
Module: 090202b
Version:
Page: 1
Comment: Objective one for manual TRANSMISSIONS states "Describe the purpose, operation and construction of a manual TRANSAXLE and and its components."
Status: Implemented

6/22/2021 11:05:52 AM
Module: 090201g
Version:
Page: 26
Comment: It states that a cam follower is a second class lever because the fulcrum is at the end rather than the middle. However the placement of the effort (cam) and load (valve spring) are not considered. A second class lever has the load in the middle and the effort at the end opposite the fulcrum. This gives allows a smaller effort force moving over a large distance to move a heavy load a small distance (like a wheelbarrow). In the case of the cam follower, the fulcum is an one end, the effort (action of the cam) is in the middle and the load (valve spring to be compressed) is at the other end. This makes the cam follower a third class lever. In a third class lever, the load travels farther than the effort which correlates to valve lift being greater than cam lift (rocker ratio).
Status: Implemented

6/22/2021 10:32:25 AM
Module: 090201m
Version:
Page: 14
Comment: The paragraph that begins with "Inspect all exhaust system heat shields..." below figure 16 is identical to the paragraph higher up on the page (one paragraph above figure 16)
Status: Implemented

5/13/2021 9:49:17 AM
Module: 090204c
Version:
Page:
Comment: Self-Test Question 6 asks which gears are used on remote final drive assemblies; this topic is not covered in the module.
Status: Declined

Year: 2020

4/17/2020 10:38:55 AM
Module: 090205c
Version:
Page:
Comment: I have had student come out of the AIT exam totally confused asking me "what is multiplexing?" as there is a question on the exam about multiplexing. There is currently no mention of multiplexing in the 1st or 2nd period modules. It was in the older 2nd period material. I believe that we need to add a paragraph or two as an overview of multiplexing to this module.
Status: Declined

1/6/2020 9:35:05 AM
Module: 090202a
Version: 21
Page: 31
Comment: Figure 34 is missing
Status: Implemented

Year: 2019

12/5/2019 1:25:57 PM
Module: 090201e
Version: 21
Page: 38
Comment: Answers for question #3 are incorrect. The picture was changed in the last revision, but the answers were not changed to match the new picture.
Status: Implemented

12/5/2019 1:23:13 PM
Module: 090201i
Version: 21
Page: 17
Comment: Figure 17 is incorrect. The picture is NOT an impeller wheel. (It is a differential drive pinion)
Status: Implemented

12/2/2019 8:45:56 AM
Module: 090201d
Version: 21
Page: 23
Comment: Answer to question #5 is incorrect. It states that bearings matched to the crankshaft should be oversized. This is incorrect. The bearings needed are undersized due to the inside diameter. The bearings now form a smaller diameter which makes them undersized. The bearing manufactures will identify this on the back of the bearing with a mark like this - 0.010us. The correct answer should be A
Status: Implemented

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