HELP Please, 92 no start, ECM Related
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 891
Likes: 18
From: Dayton Ohio
HELP Please, 92 no start, ECM Related
I was away from home and went to start the car to come home and it fired once and then died. It will not restart.
I have normal fuel pressure in the rails.
It became apparent when trying to run diagnostics that the ECM is not functioning. It will not even light the SES light (I checked it and it works) at any time.
The ECM has power available to it and good grounds as read by my meter. I tried a spare ECM that I have (it has known data link issues but functions well otherwise) with the same outcome.
I am afraid that the MEM-CAL chip has given up the ghost but I cannot prove it. I know that the chip has at least one failure mode that will throw an ECM code but I have not heard of one shutting the whole ECM down.
Is it possible that the MEM-CAL chip may have failed and is preventing the ECM from working at all? Is there something else I should or could be looking at in the car?
Everything was working fine for an 85 mile trip prior to this problem.
I appreciate all suggestions.
Matt
I have normal fuel pressure in the rails.
It became apparent when trying to run diagnostics that the ECM is not functioning. It will not even light the SES light (I checked it and it works) at any time.
The ECM has power available to it and good grounds as read by my meter. I tried a spare ECM that I have (it has known data link issues but functions well otherwise) with the same outcome.
I am afraid that the MEM-CAL chip has given up the ghost but I cannot prove it. I know that the chip has at least one failure mode that will throw an ECM code but I have not heard of one shutting the whole ECM down.
Is it possible that the MEM-CAL chip may have failed and is preventing the ECM from working at all? Is there something else I should or could be looking at in the car?
Everything was working fine for an 85 mile trip prior to this problem.
I appreciate all suggestions.
Matt
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Your year has the " luxury " of a CCM; another device in the chain that send a signal to the ECM to fire the injectors.
The CCM does a self check of non engine systems and dependent apon the fault will throw a code or may prevent engine from starting.
A bad earth on the airbag system for example will give a no start.
You need to pull the codes; they will at least point you in the direction of the fault.
The CCM does a self check of non engine systems and dependent apon the fault will throw a code or may prevent engine from starting.
A bad earth on the airbag system for example will give a no start.
You need to pull the codes; they will at least point you in the direction of the fault.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 891
Likes: 18
From: Dayton Ohio
The CCM is fine. The only code the CCM throws is a data link code which jives with an ECM failure.
I have kinda ruled out the airbag circuit because I have read out all the voltages that are coming to the ECM and they are all present. However I have completely removed the airbag from my car and had to bypass that hadny feature. It is possible that something in that circuit has slipped. I cannot remember how I did it so I will have to troubleshoot that part.
Matt
I have kinda ruled out the airbag circuit because I have read out all the voltages that are coming to the ECM and they are all present. However I have completely removed the airbag from my car and had to bypass that hadny feature. It is possible that something in that circuit has slipped. I cannot remember how I did it so I will have to troubleshoot that part.
Matt
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
No data link ; no signal from CCM to ECM to fire the injectors.The ECM has to get the signal from the CCM first not other way around.I would be looking for a bad connection on the data cabling.
Melting Slicks
Joined: Feb 2005
Posts: 2,135
Likes: 0
From: Sebastian Florida
St. Jude Donor '06
Also, those chips are pretty rugged.
You said you had fuel, how about spark?
Also, mine did almost the same thing when the pellet in my key went bad. Went to the store and then car would not start, replaced key and all good now. This is why I have always got a spare key hidden on my car.
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
You verified the Service Engine Soon bulb is good and power/ground is good to the ECM.
With the Mem Cal removed the Service Engine Soon Light should come on Solid when you turn the ignition switch to ON.
The engine cooling fan should also come on.
If you test both of your ECM's with the Mem Cal removed and the Service Engine Soon Light does not come on, when you turn the ignition switch to ON, I'd say both ECM's are bad.
If the Service Engine Soon Light does come on and the fans turn on, on both ECM's with the Mem Cal removed with the ignition switch ON, it points to the Mem Cal.
With the Mem Cal removed the Service Engine Soon Light should come on Solid when you turn the ignition switch to ON.
The engine cooling fan should also come on.
If you test both of your ECM's with the Mem Cal removed and the Service Engine Soon Light does not come on, when you turn the ignition switch to ON, I'd say both ECM's are bad.
If the Service Engine Soon Light does come on and the fans turn on, on both ECM's with the Mem Cal removed with the ignition switch ON, it points to the Mem Cal.
Last edited by Hooked on Vettes; Jun 11, 2009 at 03:51 PM.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 891
Likes: 18
From: Dayton Ohio
The ECM has to get the signal from the CCM first not other way around.I would be looking for a bad connection on the data cabling.
I did have a problem with my CCM reseting intermittently while driving last year. I fixed it by "tightening" the receptacles in the connectors. The power wire had worn enough over time to cause an intermittent failure. I have had no trouble since.
Also, mine did almost the same thing when the pellet in my key went bad. Went to the store and then car would not start, replaced key and all good now. This is why I have always got a spare key hidden on my car.
You verified the Service Engine Soon bulb is good and power/ground is good to the ECM.
If you test both of your ECM's with the Mem Cal removed and the Service Engine Soon Light does not come on, when you turn the ignition switch to ON, I'd say both ECM's are bad.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
When I was gutting out my '90 to make into a race car , the moment I unplugged the SIR connectors I got a no start ; plug them back in and it would fire up.
The CCM was seeing a fault in the SIR system and not sending the data signal to the ECM.
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Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 891
Likes: 18
From: Dayton Ohio
I unplugged the SIR connectors I got a no start ; plug them back in and it would fire up.
The CCM does not monitor the SIR system.
Matt
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 891
Likes: 18
From: Dayton Ohio
The solution
Well, I got it fixed!
The problem turned out to be a corroded connector for the battery feed to the ECM. Aparently, a previous owner had replaced the battery cable that did not exactly match the original. The mating connector for the ECM power wire did not have a good seal and corroded over time. I did not find this because 12 volts were still getting through as read by my meter, but would not get through under a load. I made a "load test" (on a hunch) and saw that the voltage dropped off completely.
It was a real head scratcher for a while but it turned out to be simple like usual.
I have to give thanks to Blue92 for letting me test my ECM on his car. That was a big help.
The problem turned out to be a corroded connector for the battery feed to the ECM. Aparently, a previous owner had replaced the battery cable that did not exactly match the original. The mating connector for the ECM power wire did not have a good seal and corroded over time. I did not find this because 12 volts were still getting through as read by my meter, but would not get through under a load. I made a "load test" (on a hunch) and saw that the voltage dropped off completely.
It was a real head scratcher for a while but it turned out to be simple like usual.
I have to give thanks to Blue92 for letting me test my ECM on his car. That was a big help.
