Possible bad ECM......suggestions please

[Amelio]

Out for a cruise today and the car started to stumble..... Fortunately I was about a half mile away from my dads house so I pulled in. I got a code 42 which I have never experienced before in 15 years of playing with these cars.

Anyway a quick search showed me it was EST issue....... Yesterday I installed an electronic FP gauge so I was moving things around the harness. I checked all my grounds and they looked good. It fired right up and ran fine.... I figure I would get it home and dive into the harness a littles further.

Left my dads house and got about 3 miles and it started breaking up real bad and then shut off. It would not re start and the SES light was flashing real fast.

This time I threw a code 51...... It started for a sec but was rough as hell an back fired bad. Another quick search and it seems it could be a bad ECM or prom....... I tend to think its the ECM since the last time I had the chip out was 3-4 years ago when I installed it. (TT chip)

Well my dad brought me to my house and I got my truck and trailer......... So what should be a good place to start? I kinda feel it could be the ECM and not a bad ground since the car has pretty much been problem free to a while.

I do have a spare ECM but I have never used it because my current ECM has the drivers installed due to my injectors.

So out of the 1 million problems I have worked through on a TR I have never seen this.........Suggestions please. What should I look at first?

 

["Reaper"]

Tune is in the chip not the ECM so unplug orange wire by battery and change ECM.

 

[Nascar83Fan]

One thing you might want to try first is check to see if the chips in the ecm are seated properly without any bent pins, if that cures the problem then it may have just been the pins on the chip that weren't making good contact in the socket making it act up. But you may still end up swapping another ecm in place after just to make sure it isnt the cause if the pins are good & the chips are seated properly. Also check to see if there are any wires coming off the connectors that plug into the ECM that may have any possible hidden breaks.
Another thing to check is if the ECM orange power wire that runs to the battery hasn't developed an intermittant wire break somewhere that also could be causing something.

Definetly make sure when you go to unhook the ECM, that you unhook the ecm orange power wire first to avoid causing any possible damage to the chips or the ECM when you're checking to see if the chips are seated properly & when you swap the other ECM into the old ones place.
That's just some ideas i had that should get you pointed in the right direction of troubleshooting it for your code 51 issue.



Posted from the TurboBuick.Com mobile app

 

[NOTSOFAST]

change out the ECM, mine did this very thing 2mos ago and it fried my pl and ttchip. had to replace all of it.

 

[hiboom]

My code 42 was a bad connector at the ignition module


Sent from my iPhone using Tapatalk

 

[Amelio]

Tune is in the chip not the ECM so unplug orange wire by battery and change ECM.[/QUOTE

 

[Amelio]

As I said I do have a spare ECM but its a stock unit.........my current ECM has the drivers installed for my injectors.

I have never tried to use a stock ECM to run the car and don't know if it would even work....so I would have to send off the ECM and get it modified for it to even work.....unless I can get my hands on an ECM that has the drivers installed to try it out.

 

[GNRick]

There are a lot of threads on code 42 if you search. Possible causes are broke white wire and or broke tan/black wire at the ecm and/or ignition module, bad translator, or bad ecm. I know there is also a white wire at the ignition module for the tach output so maybe someone can clarify if there are two white wires at the ignition module. First thing if you can't swap ecm's would be to check voltage at those wires. White wire at pin B4 should have 1.1 volts with engine running and .08 volts with key on engine off. The Black/tan wire should have 4.56 volts with koeo and 4.55 volts with engine running. You can also try swapping the esc module on the passenger side fender, although from my research on the board this appears to be the least likely problem area. Lastly, a fellow named Big Mike, who was last on the board 5 months ago, said when he got a code 42 it was his Direct Scan cable not being seated properly. So there ya go. I recently got a code 42 and the motor shut off on the hwy. Coasted off at the next exit ramp and after a couple minutes the car started up. I had been making adjustments to my translator settings so I will try swapping the translator first. Happened at setting 6 (6% rich @ WOT I believe). Let us know what you find!

 

[GNRick]

http://www.gnttype.org/maint/malf.html#42

 

[GNRick]

After a little more reading I've decided the first thing I will do is remove the Direct Scan cable from the ECM. Seems more than one person had this fix their code 42. Funny thing....a couple years ago I thought I would wire in a kill switch to the orange fusible link wire at the battery. I don't know if there was a problem with the switch or what, but the car sputtered on the hwy. just like the problem I'm having now. There were no codes set at the time, though. Actually at the time I didn't realize the orange wire was a fusible link. Now I know it was a bad idea.

 

[Amelio]

thanks for the suggestions........I will check those wires by the ignition module......as I stated I just hooked up an electronic fuel pressure gauge Saturday and when I was routing the wire I was tugging a bit on the harness right at the module.

The code 42 was the first time it stalled then it started back up and I drove it 3 miles and it shut off again...this time code 51.........I will pull the ECM out this weekend and give it a good inspection.

 

[TurboTdr3.8]

You can pull on the wires while its running at the ecm and module and see if you get a hiccup .

 

[Amelio]

You can pull on the wires while its running at the ecm and module and see if you get a hiccup .

That's a good idea......I have not tried to start it since I loaded it on the trailer....but when I went to load the car it ran so rough and back fired so bad it would not pull itself on so I had to winch it up.

 

[GNRick]

After a little more reading I've decided the first thing I will do is remove the Direct Scan cable from the ECM. Seems more than one person had this fix their code 42. Funny thing....a couple years ago I thought I would wire in a kill switch to the orange fusible link wire at the battery. I don't know if there was a problem with the switch or what, but the car sputtered on the hwy. just like the problem I'm having now. There were no codes set at the time, though. Actually at the time I didn't realize the orange wire was a fusible link. Now I know it was a bad idea.

I removed the Direct Scan cable from the ecm and still got code 42. Then I removed the LT-1 MAF/translator and put on the factory MAF. No more code 42 and car runs great. Will PM Turbo Bob and see if he can check out the translator for me. Thanks for everybody's help. I would never have suspected the translator for a non MAF related code.

 

[Amelio]

Just wanted to update you guys incase you ever have the same issue......

Today was the first time I have had a chance to look at the car........ So like I said a few weeks back the car ran when I took it off the trailer...... It ran today also.

I started it up and started wiggle wires by the ignition module....... Nothing.

I the pulled the ECM out of its holder and the car stalled!

It started back up and I then wiggled the two main plugs and nothing...... Then I touched the data cable coming out of the Power logger and it stalled again. A closer look and I saw that the PL data board was crooked. I pulled the ECM out and the PL cleaned everything and put it back together.

She's good now.......

 

[jmendlik]

zip tie that PL into the ecm so it wont move around again..or duct tape