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-   -   Transmission Ground Wire???? What's it really for? (https://www.saablink.net/forum/showthread.php?t=95706)

DC_SAAB 09-12-2014 07:12 AM

Transmission Ground Wire???? What's it really for?
 
Anyone out there notice that after entrusting someone else to do your clutch work.. that the transmission ground wire is broken? With the car running afterwards.. you just don't think about it until you see it when there's a problem.

I've been reading a lot about hard starting issues lately; and after all of that, it happens to me. Some are having problems right after they install new products on the car. Can't start the car and then point to the CPS, DI cassette or some connection that was loose somewhere. Makes sense to some degree.. but those are supposed to be pretty reliable parts.. (according to my SAAB manual, chapter 5 section B-1..lol).

Well not sure that this matters, but I recently replaced my O2 sensors, upgraded my turbo, downpipe, and fuel injectors.. basically in that order. Before I did anything, the only electricals disconnected were my battery, DI Cassette, O2 sensors and throttle body connector. Moderate work right? I put everything back together.. checked her twice, slept on it..while she charged, started her on 4 jack stands to check for leaks.. she cranked right up. Then I proceeded to bring her down off the jack stands.

Once I got her on ground.. she wouldn't start??? What the hell??.. turned over fine, but she putted (just like it sounds).. like she wanted to, but would not start.

I began my round of troubleshooting.. check this .., check that.. read codes., replace the DI cassette (spare on-hand).. then I read Blaque's (SaabLink Member/Moderator) story about electrical problems related to the grounding wire off his transmission and it made me think a little.. maybe I have something similar. Tried to start her.. but still no go. I put my old DI Cassette back in the car and continued troubleshooting.

So I already have multiple grounding points installed in addition to what's already on the car as an old ricer trick to increase the ECU response to the car.. thinking the car has got to be grounded just fine, but something told me to check to see if the grounding strap off the Transmission was still attached. It wasn't.. it was broken off.

I repaired it, then reattached.. and for the hell of it.. I turned the key and guess what.. she started right up.

Is there a chance this grounding strap is the cause of a lot of our cars not starting after major work?? I thought it had something to do with the car being elevated or running in a tow position and something in the tranny disables starting.. or demobilizes.. I don't know.

Sorry for the long post, but anyone out there have any thoughts on this???

thanks

BuHuSPG 09-12-2014 12:34 PM

That ground wire, along with most other grounds on the car, are critical for the vehicle to function. Ground wires that get crusty, corroded or broken can cause bizarre symptoms.

I always remove and clean (file, rotary wheel, etc.) grounds when I buy a new used car, and check them periodically. For sure they would keep your car from running.

BuHuSPG 09-12-2014 12:40 PM

And someone can correct me if I am wrong, but I think everything that grounds to the engine/head area grounds back to the body through that strap. I could be wrong there though.

foxracer52 09-12-2014 12:52 PM

That ground wire caused me to have an o2 sensor code awhile ago on my viggen haha after I replaced the sensor.

DC_SAAB 09-12-2014 09:58 PM

It's the weirdest thing.., because my car was running without it being attached for months, and once I do a few replacements it didn't start.


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