The Trainer  

You're reading my mind. Learning about PCMs right now because my beloved '98 Wrangler is dead because I dared splice into the wiring to install an new aftermarket gauge cluster and OH BOY am I regretting it. I fear the 'puter brayn in my Jeep is dead and am spending countless hours reasearching and parts buying and testing to only suffer increasing frustration and a reluctance to ever do my own work again. This experience makes me NOT want to buy a new car, but to buy an OLD car, one that I can fix. Everyday I hear people complaining about their (modern) cars. It seems this choice made by the auto industry to purposely complicate things is one made only of pure greed. The house I grew up in cost less than a modern car. Capitalism out of control.

Same bro. I agree 100%

It’s not so much the technology, because everything has it, it is because no one pays attention to our government and our tax dollars. Your dollars are worthless trash, they keep printing money, ( about 1 trillion every hundred days) government and big corporations are in bed together paying each other with tax dollars. You get higher costs of everything.

I agree with I just told my friend the same thing last night. If I have to spend up to 10,000 to keep my truck road worthy then so be it. I'm not paying 70,000 for a new truck now a days.

Mechanics fix vehicles, not soccer dad's or dentists. It takes a lifetime in the repair field to become well versed in auto repair. People need to stop trying to work on their own stuff, it ends up making the repair much more involved because people wanna try save a few bucks. Would you go to McDonald's and expect to find someone that can do your brain surgery?

Thank you for the kind words - I'm glad you found this video helpful. And welcome to the channel!

Did the ecm fix the problem???

@@ricksmith2476 nope. i finally broke down and called a friend who runs a shop, saying i thought it was the ecm. he said, paraphrasing: "it's the most complex component, so people default to thinking it's the culprit" turned out, when i checked the fuses in my 96 subaru legacy (my first step, btw!), i missed one: buddy brought up his wiring diagrams, and had a hunch it was fuse 15. which it was. thank god.

Thanks I will check my fuses again before I buy ecm thanks for the info I have a 94 suburban

From your mouth to RU-vid's ears...🙂

@@MotorAgeMagazine my engine had a 42 trouble code. No check engine light is on. I drained the system to try to reboot the ECM. Not sure where to start looking for the problem. I only have a 12 volt probe and a multimeter. Any advice if I need to replace the ECM? Been watching videos for days but haven't found the information that I need.

@@peacepoet1947 What year, make, model and engine do you have? Let's start there...

@@MotorAgeMagazine 94 GMC Sierra C300 with a 7.4 engine. Had code 42 and did a system drain to see if I could reboot the ECM. Code has disappeared and I will drive her in a bit to see if will give me any codes. The engine will rev up in park but in gear the timing doesn't seem to advance.

@@MotorAgeMagazine did a short idle to the Smart and Final for some whole milk to take with the aspirin I need to take for the back and leg pain.

Try www.autopcms.com for help. But keep in mind that if the ECM is bad on your vehicle, something CAUSED it to fail. You have to find and fix the cause or the new ECM won't last long.

How did it go???

@@rapvault98 I just drive it and when it goes to reduce engine power I pull over for a few minutes and then go again until it does it again... I dont have the tools or knowledge to figure it out and the mechanics around here dont seem to either. I bought a gas saver car and will hope it lasts 2 years

I18 at auto zone

​@@albertthedogeinstein7983I'm dealing with exact issue. Reduced engine power light. Pull over, turn off, restart and worked fine.... But yesterday it wouldn't restart and it cranks even after I stop turning key, won't start/run. We TRI throttle body bc code p1516 but it's not. Checked a ton of wires and voltage, fine. Taking it in bc it's probably ignition cylinder or this darm Comp ecm

HELP I bought the book.

Welcome!

same boat

did you ever get it figured out ? @marcisohm187

The P0601 is an internal ECM error code and will likely require that the ECM be replaced. I would reach out to www.autopcms.com for help. Keep in mind that you need to test the actuators connected to the ECM as well as the power and ground circuits to make sure the new ECM has a chance. As for the P0420 - don't worry about that one until the new ECM has been installed.

The Autel scope module works great and has many of the same features as the Pico.

There are DIY versions of the professional service information systems I use that you may find helpful. Here's some info I found that also might be useful: Module 1 - CCM Code 41 - Communication Error (CODE 41H History 41C Current) Problem - Central Control Module (CCM) serial communication failure The CCM requires constant encrypted data communication from the ECM at all times. The CCM communicates in a master-slave configuration, the CCM is assigned as the master and constantly polls injector and data from the ECM before startup in order for the vehicle to run and insure the VATS (Vehicle Anti-Theft System) hasn`t been bypassed. It also communicates with various other modules on the serial line reducing the number of wires required between modules.(early Canbus). This is not to be confused with ECM error code E41 (Electronic Spark Control Circuit Open) when reading ECM codes. If ECM codes (module 4) come up ERR on the LCD cluster you can scan or jump the ECM directly from the diagnostics port A,B to pull codes directly from the Check Engine Light. The C41, H41 CCM issue is mainly due to a defective ECM under the hood or open or short to ground of any of the CKT 800 (Tan) serial data communication wires and grounds between the CCM to ECM and other major computer modules behind the instrument panel. This problem can present itself on running and non-running cars depending on severity. A no start condition is typically the result from a complete ECM failure. The CCM shares serial wires and branches them from S222 behind the IP. An open or cut serial wire in the system will disable that specific module where a short will take out the entire chain. HERE IS THE INSPECTION ORDER TO THESE TARGET AREAS AND SUCCESSFUL FIXES TO THIS ISSUE: - Make sure the AIR BAG fuse is OK and I/P to DERM harness connector isn’t disconnected under the passenger footwell. Look for large yellow wires. (Confirm with ECM code 51 which also causes this code) If so the ECM will not receive power and this code will be set. Also, check CCM fuse 5% chance but easy to check. - ECM replacement. Known to solve the problem around 35% of the time (Especially if the ECM has a broken mount and has been rattling around) Replacement ECMs can be found cheap by finding interchange info for other similar GM vehicles. Make sure you swap the EPROM chip into the new matching ECM prior to installing back in the vehicle. - CKT 800 (Tan) Wires and grounds or poor corroded connectors (Usually the problem 35% of the time) - Faulty ignition control module, coils and failed linked computer components 17% (Will throw C41 codes as well) - EPROM replacement, has solved the issue in very rare cases 5% - CCM modules have a near-perfect track record and have almost never needed replacement to solve this issue. The Factory Service Manual 8A Electrical Supplementation has a troubleshooting guide for the CCM to verify proper functionality prior to replacement. 3% (As a last resort after trying everything else) Locations to check for faulty wires: - Under the drivers knee panel (hush cover) Check C68 wire area for steering column or pedal linkage rubbing-pinched and exposing wires tan wires and coming from the ALDL connector itself. - S222 Main CKT800 serial line main branch junction. Behind center of instrument panel behind HVAC unit. Very close to CCM. (Check for corrosion and clean) - Physical wires leading to ECM (Especially if the ECM has a broken mount and has been rattling around) - Wire junction area under the top of dash near right side of defrost vent up by windshield (can get corroded from moisture over time especially with existing heater cores leaks) Unfortunately this requires pulling the upper dash pad to clean and inspect junction wires and connectors

@@MotorAgeMagazine THANK YOU for this thorough explanation. At the moment, I have the dash apart and have been going through looking at wires for connection problems. I don't see any, but it is a maze under there. It kind of impresses me with the technical savvy of the GM Corvette at the time. They really are complex, but it puts me behind the 8 ball without an OBD2 port, which I was hoping that the ALDL port with the right scan tool could help. But flash codes are the best I can hope for at this point. Anyway, I will keep trying. I hope it isn't the ECM, because I just sent it out to be rebuilt and hope they did the job right. The CCM is almost impossible to access and I have very little hope of that even being the cause anyway. I hope to get his fixed and will share my experience then. Again, thank you!

@@moodberry were you able to get the work done and fix what went wrong?

@@peacepoet1947 Thanks for asking. Yes I was. But it is a long story. The lesson learned for me is that it was a combination of the ECM, the MAF sensor, and the fuel injectors. I had to buy a rebuilt ECM (they aren't made anymore). I sent it out to be rebuilt twice, but they messed it up so I went to another company that looked at it and said it was basically falling apart, which is why I had to buy one. But now it is running like a top.

@@moodberry do you know anything about a POM used in the ECM on a 94 GMC? For some reason my distributor is not communicating with it and why I get a code 42. I have DOB1 reader. I had replaced the plugs and wires but while driving to get it smogged the plug wire failed. I went to AutoZone and got another set and put it on. The engine smoothed out nicely. Timing the engine didn't work out. Tightening up the nut changed the timing back to where it was before moving the distributor. Two people suggested replacing the bolt.

Got the same problem. Gonna replace the ecm and cross my fingers

What kind of vehicle?

I had an 05 Dodge 65.9 diesel,,, no lights, no cruise, only headlights*, many no functions ,,,,, first got a new fusebox,,,,, then months later I needed that module plugged in on the side u mentioned,,,,, dealer tried 5 modules no good,,,,, rhen rhey got me A module and a new fuse box paired together and that worked**

Are you using shade tree mechanics or taking it to a shop? Just asking cause I may know a shop that could help you with that. The shop is in Decatur though

Not likely. However, the 5v reference that it uses is shared with other sensors. That could be an issue.

Carburetors are crap.

My first guess would be valve body related - improper shift linkage, solenoid fault, or something similar.

You can watch the resistance change as the throttle is opened and closed but you can only catch a glitch in the signal with a scope. A multimeter isn't fast enough.

@@MotorAgeMagazine I used the paper clip method of pulling my OBD I codes and I put the paper clip in the wrong two slots and turned the ignition on. Could this have ruined my ECM 2 weeks later? If I did damage the ECM wouldn't have been immediate? The truck turns over but doesn't start. It has plenty of fuel pressure and it is giving me Codes 15 and 32 1993 Chevy 5.0 1500K Thank you for your time.

@@mperhaps It's possible. But before you condemn the ECM, troubleshoot the two codes first. Both are circuit codes. Start with #15. You'll need an OBD I scan tool so you can view the data PIDs. With the sensor unplugged, you should read -40 degrees or so.

On late model vehicles, you can't simply install a used one. The VINs have to be matched and often the new module has to be programmed to the application.

@@MotorAgeMagazine thank you for your response

This might be worth the investment. It does OBD II and OBD I, allowing access to data stream and vehicle self tests as well as reading codes (instead of counting flashes). www.tooldiscounter.com/product/actron-elite-obd-i-and-ii-autoscanner-kit-actcp9690

@@MotorAgeMagazine hi Tnx for your quick reply but I already have a snapon mt2500 scanner AKA the brick but can’t use it to read perimeters like fuel trims and other perimeters…. Too bad

@@Phantomas2011 how are things going these days?

I'm not sure if plugging in a resistor matching the sensor's resistance will work or not - it depends on how the ECM tests the circuit and whether or not there is any kind of rationality test associated with it. As for parts, see if Duralast offers one for your Honda.

@@MotorAgeMagazine thanks, not sure what to do? It's looking like I'll have to go OEM. From my research, Honda vehicles are very particular on this part, aftermarket parts don't appear to work right. You can test these on a automotive scope for a specific sine wave, but I have no idea what's acceptable or what isn't, what the ECU rejects or not. It's like a top secret recipe... damn Hondas.

@@garyr7027 What is the code you are trying to address? Perhaps it isn't the sensor, but a circuit issue. And you can find "known good" waveforms on a variety of sites, like www.picoauto.com.

@@MotorAgeMagazine P0325 is the code, but I didn't get that code at first. My car started running really bad, no CEL and my code reader couldn't pull a code. It wasn't until I bought a scan tool that I got a code. Once I got that code, I got under the car to pull the connector off the knock sensor, and the sensor fell apart, then I got the CEL. So I replaced the sensor with a cheaper brand and it's been a issue since. Now every 400 to 500 miles or so the CEL will trip, the car runs rough, until I clear the code with my scan tool, and it'll run fine again until the CEL comes back on. The original sensor never did trip the CEL until I pulled the connector and I don't see anything wrong with the wire going too it, and that's the part that doesn't make sense to me.

@@garyr7027 Your comment that the car was "running really bad" has me intrigued. The knock sensor will not cause any drivability issues but is used to report to the ECM when any instance of detonation or preignition occurs. Is this code reoccurring and is there any other code stored or pending? (Check Mode $07 and Mode $03 on your generic scan tool).

This is really useful comment man, thank you for posting it.

I'll stick with my '73 Dodge with points, condenser and rotor!!

@@allenbeck7321 so is this some weird hobby of yours to comment on the advancement of auto technology with you keeping an antique on the road😅

@alexanderthegrape5370 no just came across this video that shows just how ignorant I am. Still have a house phone too!!!

You’ll need to understand bus networks to solve this one. But start by making sure you have power on pin 16 of the Diagnostic Link Connector

Must’ve been supplied by RU-vid, not the content creator. I didn’t get an ad at that time.

Where's a good place order ecm?? My 05 dodge ram 5.7 hemi won't start

Did u figure it out?

Good catch! The sweep is actually 40v, running across 10 divisions of 4v each (from -20v to +20v).

Hey , I see your situation happened a year ago but do you remember how it turned out ? We have the exact same car with 302,000 mi. Things are happening now at that mileage but this one is harder to diagnose . I am a mechanic .

Just decided not to worry about it, Car Has 270k Kilometers and still runs, with problems of course lol.

sometimes you can correct a problem just by unplugging the ECM and then reconnecting, making certain you hear that "click" when you reconnect the ECM.

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​@@steveolive9991 I have a 2008 Honda Civic Lx. All 4 cyl were replaced on tune up. I got a code saying all 4 are misfiring, drain bad fuel. Makes no sense. My uncle told me (mechanic for 25 years) that bad fuel wouldn't be an issue in Florida as heat would evaporate any water. I replaced my plugs & they looked okay. Still having issues. Don't know what to do now. Change the ECM? I mass air flow sensor is brand new too. What else could it be?

@@steveolive9991 Hello, should the battery be disconected when disconecting the ECM? Thank you for reply.

@@etiennebisset5642 please let me know

A "no start" condition can only be one of three things - lack of compression, lack of fuel, or lack of ignition - including any of the three not happening at the right time. Low compression can usually be heard as the engine cranks over. It will sound like the starter isn't working as hard as it should and there's no resistance when spinning the motor over. Ignition can be easily checked with a simple spark tester, available at any auto parts store. And fuel depends on the system in use - port injected engines usually have a test port or you can disconnect the line to the rail, place it in a clear container, put some eye protection on, and have someone crank the engine over as you watch for fuel out of the line. GDI engines and diesels use a high pressure system that is a little harder to check - you'll need a scan tool to read fuel pressure on these designs. DO NOT attempt to open either system without bleeding the pressure off first! These high pressure systems can HURT you if you don't treat them with respect.

The problem i have is turn key on and your check eng lite does not come on at all .its suppose to come on and go off before you start. Mine doesnt even come on there fore no fuel no stark just turns over

Did you ever figure this out my 03 jeep liberty is doing this and I was told its the fuel sending unit and fuel pump got that replaced then they realized the lack of check engine light at key turn and said it's supposed to do a self check and cycle through go off if it's good and stay on if there's an issue but never comes on to start with and it just cranks but never turns over. Originally was stalling suddenly everytime I stopped at a light and didn't keep foot on gas but then 2 days later just cranks and won't turn over completely to start

I've used this one for years...www.aeswave.com/Current-Probe-Low-range-with-Banana-Plugs-p9501.html

@@MotorAgeMagazine Thanks this helps. Purchased KAIWEETS Digital Clamp Meter and this works great above 60 amps.

Using Diag from my think car with phone. DIY option for OBD data works great.

I'd check the fuses box on the left side underhood the data lines and other main circuit run though it and they known to get corroded.

Same issue on my 2015 tiguan! Error codes p0507 and now p12a4, which is maker specific, pointing to the ecu. Any answers to your situation yet?