Hey, wanna re-wire my car?

[Brando]

I did it today. Luckily the faulty ground was very easy to replace. Spliced a new wire into the harness and ripped the remains of the old one out. The only PITA: That stupid little plastic covering in the footwell. It's just there for looks F-it. Now no-more bouncing tach. Only issue that still remains is that my temp guage reads WAY HIGH when the car's running. When it's not it reads accurately. I'm going to take Hugh's advice and pull the guage cluster out and clean the contacts. Next thing would probably be a faulty temp sender? It only reads faulty when the car is running. With the key on and the car not running it reads accurately.

Oh, and my high-amp current draw is gone. When I pulled my fuse-relay panel out a week ago I pulled a wire out of a connector and it was grounding. Fix't

[fast924S]

Sweet she will soon be at 100%, keep up the good work ;-)

[Brando]

Can't I just aim for 50%?

I'm trying to do as many free repairs as I can... Saving saving saving...

[Brando]

First, pull your relay/fusepanel out. Did I mention, disconnect the battery first? You've got a lot of unswitched hot lines right at the furthest forward edge.


Next look at the OMFG 600LBS OF WIRING?!!?! loom. Start peeling that tape off to get to the DME ground wire that runs through 2 looms. First is the main wiring harness, then there is a second set of grounds, 3 to be exact, taped together and run to the grounding point right next to the hole for the fusepanel/relay board.


THEN, undo the 10mm bolt that holds this small loom together. You can see the DME ground wire does not go very far. Straight down, a small U-turn and right back to the body. I was expecting it to go through the engine bay! I cut the three of them and crimped them into a new connector after running the new wire.


Finally, the fun part. Removing the "block" that has the fried DME ground wire into it. You can see part of the wire there, shielding toasted and the wire burnt. I went up as far as I could where the wire and shielding were still intact, cut and crimped a new line on with a butt-type connector. Run to the new ground connector and it's all gravy.


I don't have a pic of the new wires I ran. Now there's no-more bouncing tach! and I was lucky that when this ground fried it didn't melt through any of the 100-bajillion other hot lines running next to it.

[jwade944]

Electrical issues are not my strength, but with the car running, the voltage is determined by the alternator/voltage regulator. With the car off, it is the battery. Could the voltage regulator be failing? This might explain the erratic sensor as well as the fried wiring.

[ronined]

Brandon,

Thanks for the post with the pictures in it.

In your first post when you said you had a "high-amp current draw" I envisioned plumes of magic smoke leaving the wiring at an alarming rate. I think you got lucky that you didn't end up with a real mess.

As far as the voltage regulator, put a volt meter on the battery while the car is running and see what happens. If you get a constant 13V then everything should be alright with the alternator. If you read 14V, it is overcharging, 12V or less and it is undercharging.

Ed
'87 924S

[SoCal Driver]

13.8 to 14.4 VCD is a good charging rate at the battery. Have to use tenths of a volt on this.

Clean the red wires on the positive terminal -- again.

[Brando]

Still something is pulling current at all times After lastnight I could have sworn it was all gravy... I think what might have happened was that I fried something internally on the Central Electrics panel. I was corrected by my technician today... The fuse/relay panel is called your "Central Electrics" in these cars. Inside there are other connectors and wires, almost like a PCLB except with real wires instead of copper hardlines.

Tomorrow before work I'll see if I can get it started, and drive to his shop and put an amp-meter on it. Start pulling fuses until I locate what circuit or relay is junked. I had to get a jump to get it started after work. Good thing I have a reliable car to drive... my 914 :P

Edit:

Amend: While running I'm seeing 14.2V on the battery terminals. When off I see a good 12.06V on both poles. Red wire from alternator to another ground location (Engine block) I see 14.3V to 14.4V in various spots on the body and engine. I think the charging is good. When I start having bouncing tach issues I'll check the voltage then. Who knows, maybe it is my voltage regulator?

[Brando]

alright, let's recap. total of 2, for 3 possible issues to fix this.

Put my car on a snap-on analyzer. Battery checks fine, alternator failed! Only putting out ~55amps and less than 10v. Voltage regulator and/or alternator are bad

Next item, my central electrics has a short internally. Block F, to be exact... has a lot of wiring that goes to the temp. guage, oil pressure sender, indicators for them on the guage cluster, and also their readouts to the DME, tach on the cluster... It's also pulling 70 milli-amps through that block of wiring alone.

Last possible problem... DME is on it's way out. I'll address the internal short in my central electrics first, then track down a known good alternator. Lastly I will check the DME...

Electrics is a BIATCH, and I've never been good at it. But at least I learned to read Blueprint diagrams today.

Oh, and it is still technically driveable. I just can't park and leave it off or I'll need a jump...