"We Tested This PCM and there is nothing wrong with it"

Michael Mobile Technician Clinton, Utah Posted   Latest   Edited  
Case Study
Emissions
2004 Chrysler PT Cruiser 2.4L 4-spd
P0141 - O2 Sensor Heater Circuit Bank 1 Sensor 2

Are you ever afraid to buy a Chrysler "reman" PCM? It seems that often when I get called to program a Chrysler product, the programming goes fine then codes that were not there are now showing up. It makes one wonder if the time at the rebuilder is spent in the paint booth.

This week I was called to a shop to help diagnose a PCM problem. The PCM was newly replaced. The rear O2 sensor had been replaced twice and was getting a P0141. He sent the PCM back to the builder who worked on it and they sent it back saying there was nothing wrong with it.

When I got there we hooked up the scan tool and commanded the rear O2 heater on. We monitored with a labscope and got a mainly flat line with a few jumps in it. Switched to the front O2 output and got a nice square wave. After retesting the wires to the O2 sensor, it was determined there was no shorts on the powered side and the ground was good. During testing, I unplugged the rear O2 sensor while it was running. A new square wave appeared on the screen. Once reconnected, the pattern went away. New O2 sensor was right at 4 Ohms resistance. It matched the front O2. According to the service data, it was within the parameters. I condemned the PCM. It looks like the driver is breaking down when a load is applied. Sad that the company dismissed their customer so easily. Hoping that having the scope trace will convince them to make it right.

Attached is the scope trace. Red trace is B1S2 disconnected. Blue trace is B1S1 connected.

+5
Jeff Diagnostician
Cathedral City, California
Jeff Default
 

I get this on PT cruisers ALL the time!

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Danny Technician
Losangeles, California
Danny Default
 

I had a shop bring in a PT Cruiser in for an ISC issue. I diagnosed a bad driver, and the other shop had the same PCM rebuilt. When it was reinstalled, it was no different from before me removing it from the vehicle. The rebuilder ignored the notes I attached to the module. They get a lot of money for that grey paint. The rebuilder insisted that there was nothing wrong with the PCM. I insisted

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Danny: I'm glad to hear that you got paid for your efforts. Personally, I've had 4 before getting a good one from the dealer (Chrysler). Only remans were available. I've read stories of 5 at the dealership. It took 4 to get a good one for a CTS. The GM engineer, who I spoke with, told me that he needed 8 one time. I wonder how your situation would've played out with another bad one. Guido

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
 

Guido, It makes you wonder if any of these "reman" units are actually serviced or just cleaned and painted. This whole thread reminds me of a junk yard experience me and a friend had years ago. My friend Al needed an alternator for his ford falcon. We go to this local boneyard and ask if they have a used unit for his falcon. The owner of the place points a a big pile of alternators and tells

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Bob: I knew a man who was employed by a major carburetor manufacturer/remanufacturer. He told me that they worked piece work. They would go for the low-hanging fruit first. Anything needing work got thrown in a pile. When they had to, they would then work their way through the pile. Depending on their throughput, you may not have wanted product from a particular worker that day. Not that you

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
 

Yes I do have one along with other assorted carb tweaking tools. I got pretty good over time setting up various carburetors but I have to say that I'm not unhappy they went away. I really hated those cold morning no starts that flooded out. Pop the air cleaner off, prop the choke open with a screw driver, push throttle to WOT then crank until it leaned out enough to fire up. Keep throttle open

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Bob: You left out adding a gap between the plugs and the wires because it was too cold to pull the plugs outside. :) Knock the dust off of your tester and put it to other uses. Guido

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Michael Mobile Technician
Clinton, Utah
Michael Default
 

To truly "test" a PCM, you would have to load each output and vary each input exactly how it works in the vehicle. The other option would be to install in a vehicle. A rebuilder may be selling the said ECU for $150 to a retailer sometimes a three step process until it gets to you at $300. It seems that there is simply not much time to do the work properly. You would at least expect them to test

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Brin Diagnostician
Melbourne, Florida
Brin Default
 

Michael, Did you happen to notice what the heater duty cycle pid was indicating for that o2 when this was occurring?

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Michael Mobile Technician
Clinton, Utah
Michael Default
 

Not sure when running. With the DRB III test it was 100% which was not really 100%. The problem was from cold to closed loop.

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Mike: Regretfully, it is a common occurrence. Unless you're having it repaired yourself, all of the Chrysler modules are coming from the same source (dealer or parts store). I'll give you a hint, it's in my old stomping grounds. They also are the remanufacturer for GM's modules. I try to get my customers to think about the issue at hand. (They have OEM tools along with whatever else they

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Rusty Owner/Technician
Oakham, Massachusetts
Rusty Default
 

I had another shop send me an older Grand Cherokee to set up a replacement PCM once. They’d been trying to fix a dead cooling fan (likely a bad fan “relay”) and damaged the PCM driver for the fan. It came to me with a new fan motor, solid state relay, and pigtail. So I set up the PCM for them and it ends up with a new unrelated DTC that I forget now. I give the vehicle back to them And advise

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
 

That was a clever way to duck responsibility.

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Michael Mobile Technician
Clinton, Utah
Michael Default
 

It is sad to see this in an industry where we are professionals. Why can't our competitors just give us the benefit of the doubt instead of throwing us under the bus. If the customer really liked you, it could backfire and turn them on the dealer.

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Robert Diagnostician
Ballston, New York
Robert Default
 

Had a Hemi Durango that got 5 yes 5 rebuilt Mopar modules before I got a good one. Always set O2 heater codes just kept setting them for different ones or all of them. After the 3rd one I really started questioning my diagnostic abilities on that vehicle. I bet I had at least 4 hours rediagnosing that truck over and over. Finally the dealer parts person found me a new one Obviously they also

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
   

That's one of the biggest issues with crap parts, they can make you start to doubt yourself, and as you pointed out, waste hours of time on re-diagnosing. And god help you if it's a part that requires hours to R&R. Most parts manufacturers don't want to compensate your labor. It's a lousy situation that seems to be getting worse. I have had some salesmen admit to me that they are

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James Diagnostician
Bishop, Georgia
James Default
 

Amen

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Eric Owner/Technician
Edgerton, Wisconsin
Eric Default
   

I'm getting so tired of that phrase, we tested it and there's nothing wrong with it. A shop had me check out an older Corvette, 1996 I think, that was a crank no start. I connected my Tech 2 and had a no communication issue with the body module. I connected the lab scope to the com line and could see the Tech 2 send it's query and get no response. The other modules responded. Tested all

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James Diagnostician
Bishop, Georgia
James Default
 

It’s a wonder they didn’t ask you to program the VIN

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Eric Owner/Technician
Edgerton, Wisconsin
Eric Default
 

Not programmable with a Tech 2. Would have had to pull the chip if it is even possible. The shop just wanted the car gone and I was not happy with the shop, not taking my suggestion and then blaming me for not fixing it then not admitting I had it correct. I was busy for the next couple of their "emergencies" that came up. To make it even nicer, the towing company damaged the front bumper when

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Jaime Diagnostician
Ocala, Florida
Jaime Default
   

Michael, Yes, I have run into Chrysler reman PCMs with problems. I wrote about (only ) one of them. Please see searchautoparts​.​com/motorage/elect…;

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Dustin Owner/Technician
Cleveland, Oklahoma
Dustin Default
 

Yep had 99 Ram 3500 took 4 reman oem ecms before it left my shop. It would literally check a diff code than we had to start with.

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Chris Technical Support Specialist
Commack, New York
Chris Default
 

I use a Sharpie to write the fault codes on my pcm cores in the hope that the rebuilder would know what to check for. If this were industry standard, I think it would reduce the number of pcm issues after rebuilds.

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James Diagnostician
Bishop, Georgia
James Default
 

Good idea

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Jaime Diagnostician
Ocala, Florida
Jaime Default
 

Chris, you sure hold out more hope than I for those who rebuild modules! By virtue of the number / percentage of defective "rebuilt" modules that I've seen, I doubt "they" give a damn at all.

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Chris Technical Support Specialist
Commack, New York
Chris Default
 

Writing on the core is about the only thing I can do to help the situation. Even if it has no effect, the time writing a fault code on the case of the module is something I will invest in "hope"

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Jaime Diagnostician
Ocala, Florida
Jaime Default
 

I agree Chris as I know doing nothing guarantees nothing will improve. I may start incorporating the extra 2 minutes (5 for FCA vehicles) to write what I find wrong with the modules I replace. LOL

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Brian Owner
Parma, Ohio
Brian Default
 

Thanks for the Post ! I agree with the fact that most "re builders" do not do much besides sand blast and paint.. I have had a handful of that generation Chrysler PCM faulty directly from dealer usually O2 codes ( and more than I care to recall bad from other sources) One particular job that brings back some bad memories was a 03 Caravan non SKIM vehicle that was towed to a shop missing the

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