I have a 1995 base automatic that I have had problems with for about a month now.

From the beginning my car would start when it's cold and when it would get up to temp it would stall and idle eratically. I would wait about 15 to 20 minutes and start it up again just so I could get home.

So I replaced:
* the distributor
* water pump w/ thermostat
* EGR valve
* pre cat O2 sensors
* plug wires
* harmonic balancer
* I replaced the spark plugs 6 months prior

It seemed to be fine for a day and now it won't start at all. Checked the fuel pressure and it would build to 43psi and then drop to 0 in seconds.

So then I replaced:
* fuel pressure regulator
* fuel filter
* injectors
* oil pressure sensor
* I replaced the pump and dampner 6months back

After all of that it still wouldn't start. I have pulled codes multiple times where C12 Would not show every time. So I had my ECM reflashed and the car started! It ran for a couple days and now I'm back to no start! The latest codes I pulsed where:
Module 1
* H41, H72
Module 4
-
Module 9
H72, H73

Could this be a bad ECM or bad prom chip? Thanks guys

 

Is this problem fixed?

One way of telling if the PCM EEProm is corrupt would be to compare its data bit by bit with the the binary engine calibration file used by your vehicle.

The latest codes I puled were:
Module 1
* H41, H72

H41 indicates the CCM can not communicate with the PCM
H72 indicates a problem with the LCD dimming circuit. This is normally caused by the installation of an aftermarket radio.

Module 9
H72, H73
H72 indicates the EBTCM (Electronic brake traction control module) cannot communicate with the CCM.
H73 indicates the EBTCM senses a need for the Traction Control System to retard engine spark which is done by the PCM.
EBTCM DTC 73 sets if the signal line from the EBTCM to the PCM is the wrong voltage level.

Manual says if both CCM 41 and EBTCM 72 are set most likely there is a problem with the serial communication line that is used to transfer data to and from the PCM, EBTCM to the CCM. The serial line is just a piece of wire connecting the modules. Manual says you measure the serial line wire and it should not be zero volts (short to ground) or B+ (short to battery).

What you can do is examine the fuse blocks above the battery. Verify the power wire going to each fuse block is clean with no corrosion.

You can unplug the EBTCM connector. The EBTCM is located in the passenger side storage box. Also verify there is no water in the storage box. That will eliminate the EBTCM from being the cause of a serial line problem.

If that doesn't cure the problem it probably is a bad PCM.

 

I haven't checked the fuel pressure after I had the computer reflashed and the car started so I assumed it was fixed. I will check again tomorrw.

There was a lot of rust on the frame underneath the battery so I cleaned that and while I was at it I cleaned the power lines to the two fuse boxes so I know that isn't it.

I will check on the EBTCM connector and report back tomorrow. Thanks

 

Awesome to see Hooked on Vettes posting! The guy knows his stuff about this type of diagnostics. You couldn't get better advice than his, IMO.

He helped me diagnose some similar things on my '92 about 7 years ago now (!)...car had run fantastic since.

 

Was the PCM flashed in the car or on the bench? Maybe bent pins or poor connection to PCM if it was done on the bench (out of car).

Yes you're fortunate to have "HOV" (Dave) respond to your thread. He customarily sees the job to finish if you respond with quality answers. Your original post was quite complete it seemed with recent repairs and your progression to it's NOW current issue.

 

When my ECM went bad I was throwing the same codes as you. I'd say it's a pretty safe bet the ECM is acting up.

SIA electronics did the repair on my board, havn't had a problem since.

 

So I checked the fuel pressure and fuel pressure is not building at all. Could this be a faulty pump or maybe reinstalled incorrectly?

 

You can unplug the EBTCM connector. The EBTCM is located in the passenger side storage box. Also verify there is no water in the storage box. That will eliminate the EBTCM from being the cause of a serial line problem.
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Could this cause no fuel pressure build up? I'm not sure to move on to this next step if fuel pressure is a separate problem

 

Good to know I am in good hands!

 

Yes the PCM was flashed out of the car and checked all of the pins and they all appear to be in good condition.

 

Thanks for the info! I am almost %100 that it's the ECM as well.

 

If no pressure builds, while the pump is running, either the pump is 10-7(dead) or the hose between the pump and the sending unit piping is compromised.

 

Pump runs for 2 seconds. The pump was replaced back in January but I know it could still be the culprit. Do you know of a test procedure for this? And the hose you are referring to ... is that the metal lines or the replacement hose for the dampner? I just replaced the dampner on the assembly.

 

I'm talking about the replacement hose for the damper.

You could clamp your return line, make the pump run. If no pressure builds, then you've pretty well narrowed it down to the pump or the "damper" hose. All the injectors could be open, I suppose, but that seems incredibly unlikely.

If it were ME, though, and I wasn't building ANY pressure when the pump runs, I'd just go ahead and pull the pump. I'd inspect that little 2" section of hose, and if that was fine, I'd remove the pump from the sending unit assy, and I'd manually power the pump in a container of fluid an see if the thing pumps anything. If it DID, I'd hook my pressure gauge directly to the output of the pump, dead-headed, and see if the pump can build any pressure. After all that...I'd have a pretty good idea of what was going on w/the pump.

 

FWIW, if you send out your ECM I also used SIA electronics and they were very good and it did solve the issues I was having. Car runs very well now. Though my problems were not as severe as yours. Also I once had the communication error code between ICM and EBT. There is (at least on my 92) a sleeve of wiring that runs along the drivers rocker and wraps around under the rear wheel well. Sometime it simply rubs on that well and can cause damage. Honestly I moved mine around to inspect for damage and since haven't had the code. That code also coincided with an ABS light though. Hope that helps good luck.

 

So I went ahead and bought the FSM which has been a good investment. I followed the procedures for code 41 and have found out that it is for sure an intermittent problem.

I ran multiple test procedures with the FSM as my guide and all signs point to faulty PCM. So I have 2 options: Get a reman from orielys which is an A1 cardone PCM or go through rockauto.com and get a OEM reman ACDelco. Any thoughts or suggestions on the better route or does it not matter?

 

I'd maybe try to find a used PCM local to me. A loaner from a fellow "user" here on the CF might be preferred BUT regardless of your purchase be sure to retain what you've got until you have the car running well and consistently. I'd avoid maybe both of your purchase choices and see how closely a "dealer" local to me could maybe "price-match" your other choices. I'd consider maybe a premium price for the local buy.

Was yours done on the bench "local" OR did you send it off? If sent off - who?

There's an offering on eBay that includes the repair, the most recent GM FLASH, VIN confirmation and a 1 year warranty. I'd maybe have a conversation with them if it came to needing a purchase and you truly believe yours has failed. It's maybe NOT how I'd go about it BUT if they're everything they claim they are it's maybe something to consider. An eBay search for 16181333 should get you the offering. A "conversation" certainly might be quite useful.

Your RA or O'reilly buy requires a "flash" after purchase so .........

 

It was sent off. I took it to NAPA and they sent it to an affiliate of theirs named Car City. I provided them with my VIN and mileage and got it back same day for around $50.
I assume the affiliate of Napa's is certified or else Napa wouldn't do business with them. If I were to take it to the dealer it would cost as much as the unit is to flash. Is there a way to find certified shops in my area to make sure it is an up to date flash?

 

I'd think then maybe you have a conversation with "Car City" and explain your situation and you'd like them to confirm their FLASH. They should be able to do that for you if the FLASH was supplied by an ACD TECH CONNECT service or another service. The OE/GM FLASH should be available to most that offer "bench FLASH" for other retailers. For sure? No

If NAPA turned it around in a day then Car City is certainly local. Ask to speak to a TECH maybe ... ask if they confirm PCM in any fashion before the FLASH or it's just that a FLASH.

Based on a RA buy, another FLASH from the "local" you're over the price of the eBay offering I mentioned. A conversation and the WARRANTY might be a reason to consider them. I don't know them but I'd think a short conversation or a couple email exchanges might "hint" their talent.

 

Is your fuel pressure fixed?