I Took my 2005 Caravan for the IL emissions test. They were not able to get any readings from the OBD. All monitors show N/A. The Dealer told me to check fuse and test battery. Both checked out fine. Still no readings. The dealer tried to flash the PCM with updated software but it wouldn't load. They tell me to start by replacing the PCM.
The van runs great and the check engine light does not come on.
Would you agree that the PCM could be the problem? Could you also explain the steps to remove the PCM?

 

changing a PCM raises other problems unless you have the ability to flash program it to match the vehicle. I highly doubt that the PCM is bad because you are not getting codes. We don't know what the 'mechanics' did to diagnose the problem, but if you have no communications, there a some specific testing proceedures that must be done first. I'd be testing all the pins in the DLC and verifying the results are correct per the factory service manual. So if there's something wrong with the wiring to the DLC, of course there will be no communications nor any ability to flash the PCM. When I do diagnostics related to computer issues and I get to a point where I'm lead to 'replace computer' I start over from the beginning to make sure I didn't miss something. I got burned once on changing a computer that the diagnostic routine sent me because I misread a result... So when ever I get to 'replace computer' I start over and make sure I didn't miss something.... it really isn't a very common for a computer to fail... yes they can, but there's a lot more things that will lead to a problem way before the computer. It's like these trannies. I can't count the number of times 'mechanics' install a new rebuilt trans for some stupid electrical problem. Always properly diagnose before throwing parts at it.

 

I was initially thinking it could be the wiring to the DLC. I spoke with the service directer and he insists that the tech made the proper diagnosis. Is it possible that the vehicle runs good with a bad computer?

How do I tell if the van has the SPEC or NCG type PCM? Could it possibly be a loose connection at the PCM?

I'm considering buying a refurbished one online flashed with the most current software, milage and VIN.

Thanks again for any advice or direction.

 

doubt if the computer would just go bad, cause no communcations and still run. If you want to buy a computer off the net, I'd think twice... what if it doesn't work, what if thats not the problem... you have less than a 33% chance that buying some other computer will fix the problem. Again, if it was me, I would definitely trouble shoot the system. If my scanner showed 'no communications' I'd use problem solving techniques to determine why and a computer replacement problem would be at the very bottom of my list.

 

I just hooked up a pocket scan tool and got code U110C - NO FUEL LEVEL BUS MESSAGE. Every other time I have tried to scan, I got no codes. I did have the negative battery cable disconnected though because as I was poking around at the PCM.

I'm caught in the middle. Should I not trust what my dealer is telling me?

 

so if your doctor told you that you have cancer, you'd just run out and get treatment, or would you get a 2nd test done?

 

2005 should be a NGC controller. But remember everytime you disconnect the battery you are also clearing the memory for the emission monitors as well any stored codes. I agree with 92dak5.24x4, the problem maybe in the DLC. The way to ck to see if you have an NGC controller is to look up inside the driver side fender. If you see four or five connectors,then you have a NGC connector. One of the connector is for the transmission. But if you see a controller behind the driver side headlamp assy. spec controller.

 

What could I check to the DLC? It is able to provide power to the pocket scanner. It returned U110C code yesterday, probably because the battery was disconnected. The CEL is NOT on. Are there some simple checks I can do?

Thanks again...

 

using a factory service manual and a dvom, you can do a lot of things to check the dlc and communications. since you have a code reader toy, try disconnecting one of the engine sensors and drive the van. this will verify the MIL works properly, and then you can use your toy to see if the proper code is set. If you disconnect the coolant temp sensor or throttle postition sensor, this would be 2 easy access sensors to do an experiment.

 

I will try one of those sensors and report back. I need to correct myself. The CEL DID come on for the U110C code. I drove the van this morning running some errands and it shut itself off after a few engine starts.

Thanks for your guidance.