924Board.org

[Lizard]

if when your car is on and you gas/ temp gauge moves when you step on brakes, turn on lights, or put car in reverse, there is very little info on this the haynes manual doesnt say anything about it and the only spot on the net that has the fix for it doesnt give all details.
to fix
first in the back right in between the lights there is a 4 post groundclean the terminals on there and replace female connectors, 99% of the time these are still factor plugs and the copper loses its stiffness and all of its conduction. if it still happens under the dash just infront of the fuse box there is another ground connector like the one in the back, this one has 6-8 terminals on it and is kind of hard to get at so i would suggest removing the fuse panel, again clean terminals and replace female connectors, this will fix that annoying little problem.

if anyone has any other suggestions to fix other electrical problems please post them here as i would like to make a collection of troubleshooting for myself and others

[Benski]

It helps immensely to add a ground strap between the cylinder head and the little post in the battery well.

I've been told by several electrical engineers that it might also be worthwhile to run a long, thick cable between the engine block, the grounding ring under the steering column and the grounding ring in the back.

I've also been told that the reason for all of these problems is the galvanization. While it keeps the body from rusting, it makes everything else rust twice as fast =)

[larso]

The galvanizing properties of these cars, and some metals in general also leads to the metal having a "layer" on it; oxides, etc., so it LOOKS as if you have a good connection, but if an oxide is there it will stop conductivity. Female battery terminal connections that are gray, but not shiny, are a good example of this. The copper spade connectors that are old will have a layer of brown oxide on them and look as if it is metal to metal when it is actually not. It is not very good to wire these connections down and clean them, as it takes forever, you risk breaking them off. Just cut, strip, and replace the spade. The other problem is internal wire "crapping out". Basically, the wire looks good on the outside, but inside the coating, it may be all green or rusty. IF the coating on the wire is very hard, this is a sign that it may be bad on the inside. Some of the brown ground wires in these cars are too thin to hold up for 20+ years.

The only thing conducting the head to the block are the head bolts, and the manifold bracket if you have one, but the manifold bracket is painted. If the head bolts are rusty, or soaked in oil, or coolant, they will have a hard time conducting to the aluminum head. Especially if the block is also dirty where the bolts have been thread in. Must be why adding an engine ground strap to the block sometimes helps significantly, and sometimes it just helps a little.

[ This Message was edited by: larso on 2002-05-19 16:18 ]

[abduln]

Thanks for the info guys

In my case my electricals are great, except that when I turn the headlights on, or activate my blinkers, my oil pressure gauge drops more than a bit (it's strictly an electrical issue, oil pressue is fine), and also my volt meter reads 10 volts, though I tested for 12.5 at ldle.

Any pointers on where the trouble spot may be? I will eventually tear down the wiring, just not any time soon. I may even replace the wiring with a painless wiring kit, just so that I can get fresh wire for the entire car.

Thanks, and regards.
Abdul

[Lizard]

abdul when your car is sitting idling the voltage at your battery should be between 13.5-15 volts anything else you should check regulator and alternator

[abduln]

Thanks, I am pretty sure my alternator/regulator is fine. My 12.5 volt reading was probably just because I needed to adjust the needle on the analog multi-meter.

My overall problem is that I don't have a voltage drop over the entire system, some short is specifically a affecting the volt meter and causing it to read 10 volts. I noticed that sometimes it reads fine even with the headlights on. I guess it's an intermittant short and I will have to trace and replace suspect wiring

Thanks again.
Abdul

[Lizard]

i am almost certian that it isnt a short and that it is a bad ground that is a madger problem with this car probably the worst

[924RACR]

Yes, additional grounding for the engine block to the firewall is a wise thing, as is the additional ground strap for the dash. I have both of these in my racecar, as well as other fresh wiring or contacts for grounding, and my oil pressure gauge does not drop when I turn on the lights. Interesting, seeing as how I don't ever use the lights! LOL

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Lizard]

where do you attach the ground to the dash on your car as i need to intall that but i was thinking about just adding grounds sraight to each componant however just one big ground would make it alot easier

[924RACR]

Yeah, it's just one big ground - 10ga or better. I went behind the center gauge cluster, spliced into the ground for those gauges (it's a common ground for all dash gauges and lights) and ran it up behind the center speaker to a ring terminal, which fits perfectly onto the stud on the firewall behind the speaker. This is the stud that secures the dash in the center.

I think it's mentioned somewhere in the FAQ or Tech Section.

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Lizard]

thanks i will be doing that tonight, any other suggestions

[Joes924]

sounds good guys.