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DSPTurtle's Avatar
 
Join Date: Jul 2001
Location: Suntree, Florida, USA
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Help Electrical Gremlins

Hello Pelican Braintrust,
I am hoping that someone here has already solved a similar issue and can give me a hint...
I have a gremlin in my wiring somewhere.
Symptoms
1. Radio Cuts Out... kinda like it saw an over voltage. It makes a soft pop and shuts down.
2. The tachometer starts whipping back and forth from 7000 to zero and back again.
3. Low beam headlights do NOT work but high beams do (this is a constant situation, not intermittent like symptoms above).
4. Happens when driving straight down the road... no big bumps or turns seem to set it off more often.
5. Happens about every 20 minutes, but NOT with predictable regularity.
6. Voltage draw goes way, way up when turning on the H4 headlights. Normal running voltage is about 13.8 but goes to 12.1 when the headlight switch is pulled out into the on position.

After about 20 seconds the radio comes back on and the tach goes back to normal. The radio does not lose it's memory so it must be consistently getting the keep alive voltage (I think).

Other Pertinent Info
1. I just changed the turn signal switch and don't remember this problem before that replacement. I am sure that all the wires went back to the same spots they came from. Everything worked fine for about two days. Turn signal switch was changed due to the fact that every time I put on the turn signal it would engage the high beams as it cancelled the signal. Also, high beams did not work in the intermittent (pull back on stalk) position. After the swap, everything worked perfect... for two days.
2. I have H4 Headlights, but do not have a relay in between the fuse panel and the headlights.

I am currently poring over electrical diagrams trying to find a common circuit, but if someone has a shortcut on how to fix this I would be much obliged
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Old 11-19-2011, 08:09 AM
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i have absolutely no idea about some of that stuff, but, i did have a similar problem with my headlights...they would come and go, sometimes bright, sometimes super dull...

i replaced the switch with a buddies and same thing...

i replaced the headlight fuse with a new one, and cleaned the grounds in the front corner of the trunk, and problem hasnt been back (knock on wood)

hope this helps, but its the best i can offer man, good luck! i know how frustrating this can be,...
Old 11-19-2011, 08:15 AM
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Tach jumping is often the result of an over-voltage in the engine compartment, not necessarily at the battery. Battery is a HUGE sink for charging voltage/current, even moreso for over-voltages.
Old 11-19-2011, 08:35 AM
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JB:

Sounds like you are back-feeding somewhere. Try to isolate it by driving
during the daylight without any head lights or parking lights on and see if you
still have the issue. That should tell you if it's in the lighting circuit or not. I
would also be sure to wire in a relay for the H4's at some point in time.

If you still have the fault start pulling fuses one at a time for everything
operated by that same switch and take a drive in between to try and isolate it.

Check all the ground connections for all the components operated by the switch.
Also check any piggybacked connections on either of the battery terminals.

Check the pin connections on the 14 pin connector in the rear as well as
the coil connections.

I hate those types of situations, biggest pain in the ass there is, Good Luck !!!

Cole
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Last edited by cole930; 11-19-2011 at 09:07 AM..
Old 11-19-2011, 09:04 AM
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Do these cars have an X contact relay like the VW's of the era do? This is the relay that runs the accessories with the key in the on position.
Old 11-19-2011, 09:13 AM
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I can't offer a damn thing other than what's been proposed. I hate electrical gremlins, those nasty SOB's.
One comment on over-voltage causing tachs to jump around: I don't see that, with my admittedly going-south voltage regulator that is prone to charge really f'ing high voltages once the temperature gets high enough for the regulator to act up. The only over-charging symptom I get is erroneously low AFR's and a stink of hydrogen sulfide gas as the battery cooks. Everything else works fine when that happens.

First and most simple thing: check and clean and tighten all ground straps.
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Old 11-19-2011, 11:40 AM
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Coincidence, cause or result???
My CDI box fried today causing me to have to be towed home. Apparently the R2 resistor gave up the ghost. I ordered a few from Mouser so hopefully I can get it fixed sometime this week.
But, the question remains for now... was this the cause of my electrical gremlins? I can buy the tach acting weird being related to the CDI... however, the headlights??? No freaking way.
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Old 11-20-2011, 10:06 AM
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