[DeTomaso] Techno Question: Electrical gremlin help

[Thomas Tornblom]

Charles Engles wrote:
> Dear Forum,
> 
>           I am faced with a new gremlin.  A variable gremlin, not a non functioning one.   I installed some new GT4 taillights from Larry Finch and made sure to ground them well.  They have been working fine.  Now, on a two hour trip yesterday, they didn't work at the start and after an hour, they started working.  Today,  they started with a one or two blink response (same on both sides) and then quit.  They would repeat this about three or four times and quit altogether.   On the return trip home (after the engine and the electrical system were "hot" [??} ), they began working again.   I just tested them in the garage and they will flash about four or five times and then cease.    After about four tries, they cease altogether.   
>          Could this variable, intermittent malfunction be due to the dreaded ground problem at the legendary common ground bolt rumored to lurk up under the dash in "no man's land"??

I doubt that the ground bolt under the dash would have anything to do 
with this. You would probably see some of the other lights flash faintly 
if it is a grounding problem.

Do both lights show the same behavior?

One possible problem source is the junction block inside the right rear 
fender, somewhere near the water bottles.

My brake light didn't work at the annual safety inspection some years 
back, and I started checking at the switch, where there was voltage, and 
at the light, where there wasn't any. Checking the wiring harness layout 
in the spare parts catalog showed that there is a junction block 
somewhere in the rear, and that was it. The connectors were gritty and 
slightly corroded. Cleaning and squeezing them slightly fixed the problem.

With the lenses removed, try to measure any voltage between chassis 
ground and the bulb ground when the problem shows. There shouldn't be 
more than a few hundred millivolts nominally, but if you have a 
grounding problem, you would see +12V there.

> 
>               I hate electrical problems,  Chuck Engles
> 

Thomas