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Discussion Starter · #1 ·
Yesterday they were OK, today the coolant temp and brake fluid warning lights are coming on and going off both together and at random intervals and the tach acts like we are in the Bermuda triangle swinging wildly back and forth. The brakes are fine as is the coolant temp according to the gage. What do these three instruments have in common? :confused:
 

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Discussion Starter · #6 ·
The Elves are tied up this time of year. I'm going with the ground theory.
 

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Or maybe ...

:rolleyes:...just ground the elves!!:D:D:D
 

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Since the elves are busy I'm going with gremlins. Either that or the system is out of smoke.

+3 to grounds....
 

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Trained (ex)Professional, , 1953-2018 RIP
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What do these three instruments have in common? :confused:
After looking at the diagram, it appears that the only thing in common is the monopod circuit board.
External wiring would not appear to be the cause of the problem as the coolant and brake warning lights attach to the board thru connector A, the tach signal at connector B and gauge power and ground are thru connector D. If it were a power issue, all gauges and most warning lights would be effected. Same if a ground problem. In addition, the coolant and brake warning lights come on when their respective sensors provide a ground.
Having said that, I'd lean toward the monopod being the problem (but I've been wrong before).
 

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After looking at the diagram, it appears that the only thing in common is the monopod circuit board.
External wiring would not appear to be the cause of the problem as the coolant and brake warning lights attach to the board thru connector A, the tach signal at connector B and gauge power and ground are thru connector D. If it were a power issue, all gauges and most warning lights would be effected. Same if a ground problem. In addition, the coolant and brake warning lights come on when their respective sensors provide a ground.
Having said that, I'd lean toward the monopod being the problem (but I've been wrong before).
Would you say monopod or engine ground since a majority of those get ground from the sensors on the engine? I was thinking, at first, maybe, g forces, till he complained the tachometer was doing the same thing, I've read a few threads on here when someone turns their temp guage goes up and down and others that said the same thing about their brakes-fluid moving to the front side of the resevoir making the float drop...:confused:
 

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Trained (ex)Professional, , 1953-2018 RIP
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I considered engine ground as well but ruled it out because;

A) a bad engine ground would effect the coolant temp light (and possibly the tach) but not the brake warning light.
B) no engine ground would result in the coolant light not turning on.
C) the coolant temp and oil pressure gauges would also be effected.
D) the gauges are grounded to the chassis at connector G54B (not engine ground circuit related).
E) the brake warning light, having switched power, turns on when connected to chassis ground G54B thru the low brake level switch (again, not engine ground circuit related).
 

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But Mad North-Northwest
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IIRC, the coolant temp and the brake lights are the ones that come on when you start the car, then fade out. When they started coming on randomly for me while driving it turned out to be a low amperage condition caused by a loose battery clamp. Check them for tightness and also clean up the negative battery ground.
 

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Discussion Starter · #14 ·
Thanks to those of you that provided non-smartass possible solutions...however, the problems stopped as quickly and mysteriously as they started so it appears it was elves and/or gremlins. I will check the battery terminal connections though. :D

Ken
 

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I would check the connectors at the cluster itself. If you have a ground issue it will do weird things as electricity seeks the path of least resistance. Sounds like a loose connector problem.
You would be amazed at the crazy stuff I see on cars from ground problems. Had a car the other day that had a "lazy" ground (meaning not quite bad) in the drivers door latch assembly that was turning on the upshift arrow in the cluster when you would close the door.

Worth a shot to clean the connectors and make sure that they are tight.

Paul
 
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