Can't read SES codes

[MuRCieLaGo]

Hi,

'91 ZR-1

Just finished installing headers and Marc Haibeck's chip. I didn't connect the exhaust system to the headers yet.

When I started the car, I forgot to plug the connecter under the ECM. So it ran pretty rough. Now everything is plugged, even the small vacuum line going under the ECM.

I got a SES light (and a SRC). I managed to read the SRC light with Dynomite's Code Reader (13,14 then I stopped at 14 because I'm pretty sure it will show all codes) but I am unable to read SES codes, even with the paper clip method. It worked fine before installing the headers.

However, when I removed the chip to send to Marc Haibeck, i accidentally unpinned a wire going to one of the ECM connectors, as you can see on the picture.

Should I tow my car to the nearest electrical shop, to have that wire pinned back? Could it be the solution to my issues? Black and white wire.

Thanks guys!

[WVZR-1]

I believe BLK/WHT is ground and there should be maybe 3 at the ECM, R6, R17 and G12.

R = red connector G = Green connector I believe on a '90/ A '91 I'll look in the AM.

Look in your FSM 8A-22-3 or so for the ECM. Do you have an FSM?

*** I checked the '91FSM - 6, 12, 17

[MuRCieLaGo]

Yes, I got a FSM. But I won't pin back that wire myself - electrical shop will do (with FSM). I'm just wondering if it will be the solution...

Thanks a lot for the pages in the FSM though.

[WVZR-1]

Originally Posted by MuRCieLaGo

Yes, I got a FSM. But I won't pin back that wire myself - electrical shop will do (with FSM). I'm just wondering if it will be the solution...

Thanks a lot for the pages in the FSM though.

Don't tow without speaking to shop first. I doubt they have the terminals needed. I may have a solution for that but you'll need terminal(s), seal(s) to assemble and repair.

A solution to your problem connecting the ground back to the ECM? Well there's no guarantee BUT it's "busted" so ................

[MuRCieLaGo]

I played with the wires a lot on my RX-7, and it quickly became an absolute mess. I don't want it to happen on my ZR-1.

I'll speak to the shop this morning. I'll hit you up if they can't help me.

Thanks a lot!

[WVZR-1]

Originally Posted by MuRCieLaGo

I played with the wires a lot on my RX-7, and it quickly became an absolute mess. I don't want it to happen on my ZR-1.

I'll speak to the shop this morning. I'll hit you up if they can't help me.

Thanks a lot!

I seem to recall you "junkyarding" a connector for your car awhile ago. Was that you?

This is what I'd do - all '88 -'93 W-body GM's used a '730 ECM in a weather-proof case like the Corvette '727. The ECM was mounted in front of the RH strut tower. Go "junkyarding" cut yourself off a couple connectors maybe paying attention and getting one with a BLK/WHT, put your hands on a correct release tool and remove one from the JY donor, remove the terminal in yours, insert the one removed from the JY connector "twist/tape" for diagnostics.

W-bodies = Grand Prix, Lumina, Regal, Cutlass Supreme

Your shop is NOT going to have the correct "gold-plated" weather-proof terminal. I'll betcha!

You want a release tool for a Metric-pack 100 NOT just a generic and you'll have a connector from the JY to experiment with before messing with your ZR-1. There's 22 terminals I believe in each connector so there will be "lots of practice" for you before you even touch your ZR-1.

I haven't actually attempted the swap I just mentioned but I'll betcha' it will be OK.

If you do the JY thing when you're looking if the ECM connector covers are still in the car grab a couple. They're the same as the later C4 Corvette and ZR-1 I believe also.

12031876 is a correct release tool or it's equivalent from somewhere. GOOGLE might be your friend here to find options.

https://theelectricaldepot.com/weath...4a2fb91a9b1b1c

This is what I believe/hope you find in the W-body car under the hood - an easy grab!!!


W-body ECM.jpg

Hey Cliff - you got your eyes on this?

[Dynomite]

Originally Posted by WVZR-1

This is what I believe/hope you find in the W-body car under the hood - an easy grab!!!


Attachment 5165

Hey Cliff - you got your eyes on this?

That is a 95' ECM harness cover I just bought on Ebay as my cover was modified.
Never accidentally unpin a wire going to one of the ECM connectors !!!
I am watching and learning as you speak

What I would do is stick a pin in the socket and alligator clip the wire to the pin and then use the Code Reader to make sure that is the problem before I go further. Just Saying

[WVZR-1]

Originally Posted by Dynomite

That is a 95' harness cover I just bought on Ebay as my cover was cut.
I am watching and learning as you speak

I've never done this but I've done I think similar for base C4's before. I don't keep many notes, I figure if I've done it once I should be able to stumble through it again or find the information again. I lost a HDD recently that I had no back-up for and lost a good bit of the "notes I did keep".

It's harder to research the LT5 ECM information because all of the interchanges are done based on requirements of the ECM and not it's basic build.

The OP wants to TOW - I was trying to give him what would do diagnostics AND a repair.

There's many that have done what the OP did - your comment in BOLD means you never have OR is a warning to others not to accidentally?

These should be the go to cars and drive-line the R, W, T & V would be the 8th digit of the VIN

1990-92 2.5 L4 TBI “R” LR8 (“W” body)
1988-89 2.8 V6 PFI “W” LB6 (“W” body)
1989-93 3.1 V6 PFI “T” LH0 (“W” body)
1989-90 3.1 V6 PFI turbo “V” LG5
1990-91 5.7 V8 TPI “8” L98 (“Y” body)

[Dynomite]

Originally Posted by WVZR-1

I've never done this but I've done I think similar for base C4's before. I don't keep many notes, I figure if I've done it once I should be able to stumble through it again or find the information again. I lost a HDD recently that I had no back-up for and lost a good bit of the "notes I did keep".

It's harder to research the LT5 ECM information because all of the interchanges are done based on requirements of the ECM and not it's basic build.

The OP wants to TOW - I was trying to give him what would do diagnostics AND a repair.

There's many that have done what the OP did - your comment in BOLD means you never have OR is a warning to others not to accidentally?

I have hot wired the ECM I think Pin 17 with a pin to check secondary operation but other than that have never had electrical issues with ECMs. I DO watch closely the ECM Connectors when I turn the ECM over to remove the CHIP.

He could essentially Hot Wire that broken pin to check codes and then even fire the LT5 up and check fixes for codes. And if that works....just drive it rather than tow it (I would use my Tow Bar if he wants to tow it) anywhere he wants.

[MuRCieLaGo]

The (car) electrical shop is well reknown where I live. They pinned back the wire, and now everything seems to be fine on the car. No more SES, no more SRC.

I identified the repaired wire. If something goes wrong again, I'll use your infos and go from there.

Thanks a lot WVZR-1 and Dynomite, I appreciate your help.