Electrical Nightmare

[Miami240z]

I have a thick ground wire on my lower sr harness that Im not sure where to place. It extends furthest to the front of the car and is close to the passenger side relay/fuse box. When its disconnected the car is dead and when i bolt it to the intake manifold the car behaves as described below. Been searching for anything sounding close to my problem for days with no luck.

SR redtop starts up great in my 93 coupe. Few bolt on mods nothing too serious. Car idles and revs fine under no load. go to test drive and notice my lights dim and temp gauge needle jumps when i press the brake. Put the parking brake down and the temp needle shoots above and beyond Hot. Im certain the car isnt over heating so i proceed. Start to reverse and hear a buzzing+ticking sound that increases in speed the faster i go. Sounds are coming from my passive belt computer, ecu, and somewhere beneath the steering column. Sound is present going forward as well. Car also feels like exhaust is all blocked up by 2.5k-3k rpm.

Any ideas? Feedback greatly appreciated.

[mxsx25]

if you can get your hands on a short finder (about 250$ from mac tools) that would probably make your life a hell of a lot easier and alow you to fix the problem w.o removing dash, panels, etc. ... just a thought though, good luck

[TRUSE-R]

Its hard to tell exactly what the problem is but, you may what to double check all you plugs/connections if they are seated properly & that includes the plug @ the ECU. Prior to this was the car running perfect? When did this start happening?

[Miami240z]

this car had another redtop sr running in it. It didnt have the problems it has now but it wasnt running too well either. This started with the new motor after swapping the lower harness for the old one as the wires were cut on the one currently in my engine bay. Like I said theirs one black ground on that harness that im confused as to where to put. Do any grounds from that harness go to the chassis or do they all bolt up to a part (starter, alt, etc.)? Thanks for the input. I know this is one hell of a gremlin.

[Miami240z]

Dug up a diagram of the lower harness. Picture is showing that the ground is supposed to be connected somewhere on the chassis where I have it bolted to my intake manifold. Going to try finding a solid ground on the body and see if it solves the problem.

[Miami240z]

Still haven't found the problem... Car starts, idles, and revs under no load without a problem. Push the brake... temp gauge rises a bit... put down e-brake and it rises half way. Put clutch in and put in reverse and the gauge rises up and past hot. Moving forward and reverse makes my lights and gauge needles jump and flicker in unison. Bell also rings continuously after moving the car as if its off and the key is just an ignition even though its running. May try posting a vid somewhere so you guys can see this nonsense. :bash:

[PhopsonNY]

this might help

http://www.bimmerboard.com/forums/posts/171281

[Miami240z]

Thanks a lot PhopsonNY. Looks like a promising troubleshooting method for my problem. Please excuse my noobness lol. 6 motors swaps under my belt and none have been this FUBAR!

[PhopsonNY]

no sweat man... just went through two days of electrical problem solving after a major overhaul of my car.
Had pulled the engine, fixed all rust spots, improved on others, resealed and repainted everything and upgraded all sorts of parts.
Found some many electrical problems when I went to drive it and some dated back to when I had my swap done.

I am surprised the car actually ran before.

Anyway, good luck, it is a pain, but gratifying once you have found all the problems.

[Miami240z]

This sh*t is really bustin my balls... The only thing new with my setup is the lower harness which came cut. I used the one from my previous redtop SR that was running without any kind of electrical problems. I have one thick black wire with a O- connector on it. It must go somewhere on the motor as a ground but im not sure where. The wire extends way far out like the plugs that go to the fuse box. Cant find anything on it. Searched through a AT to MT swap guide for info but nothing... Im sure I sound like a newb but I got more hands on experience than most of the "Tell me how to solve this problem when I dont explain the symptons clearly and dont bother searching" types. Only ask when the brain and hands are fried from working/ researching.

[krazydriver]

As you'd mentioned, i can't think of any grounds in that area that run to the body.

Any possibility it's the ground cable to the alternator?
If your alternator doesn't have the ground cable attached i'd expect it to generate alot of electrical noise, which could cause the problems your describing?
I'd check to see if the alternator ground is hooked up, if not try that.

[Miami240z]

If im not mistaken there are 2 grounds and a plug on the alternator. All of which are on snug. This cable reaches further towards the radiatior and is part of the cluster that runs to the fuses on the passenger side... gonna find the link to a pic of the harness.

[Miami240z]

Im such a f*ing retard... chassis ground located behind the valve cover was unplugged. All problems including dimming lights, clicking relays, and erratic speedo/ temp gauge have been solved. SR20s are so picky about the grounds Im pissed I didnt check back there from the start. Thanks for the input guys.

[952jz240sxr]

i had a prob like that when i swaped my motor to another car.
you can try this. if you have a set of jumper cables connect the red and black to your ground post. connecto one of the other ends to the block and the other end to the chasis. see if that helps. if it does your missing a chasis ground..