| Author |
Message |
Steve Magnusson (91tr)
Intermediate Member
Username: 91tr
Post Number: 1956
Registered: 1-2001
| | Posted on Sunday, July 13, 2003 - 1:22 pm: | |
If the electrical connection from the instrument cluster ground to the chassis ground isn't great (and it never is), turning on the parking lights can "pull up" the instrument cluster ground to a small positive voltage (altering the gauges' reference). IME the design and execution of providing a good electrical connection between the instrument cluster ground and the chassis ground is marginal at best (and poor if disassembled/molested) so you might check this in this case (if the change was 1/2 a needle width I'd say "normal" and wouldn't even worry about it). |
Bill White (Nc_newbie)
Junior Member
Username: Nc_newbie
Post Number: 142
Registered: 2-2003
| | Posted on Sunday, July 13, 2003 - 12:57 pm: | |
Check to see if the head lights affect it. I don't think it is a short. But rather a bad connection somewhere. The additional load of the parking lights is probably dropping the voltage going to these gauges. Check the voltage at the gauges with parking lights on and off. |
stu cordova (Balataboy)
Member
Username: Balataboy
Post Number: 469
Registered: 4-2001
| | Posted on Sunday, July 13, 2003 - 10:55 am: | |
Thank you....
Which terminals would you think need cleaning?
How would you test for this possible short? |
'75 308 GT4 (Peter)
Advanced Member
Username: Peter
Post Number: 2911
Registered: 12-2000
| | Posted on Sunday, July 13, 2003 - 12:43 am: | |
Hmmm, some kind-of electrical short somewhere in the dash wiring, or in the fuse box(es). Sorry if that sounds really vague, but that's what I think would be a cause... |
Andrew A. Illes (Andyilles)
Junior Member
Username: Andyilles
Post Number: 167
Registered: 10-2002
| | Posted on Sunday, July 13, 2003 - 12:42 am: | |
Stu.... time to clean some terminals.
Best regards,
Andy |
stu cordova (Balataboy)
Member
Username: Balataboy
Post Number: 467
Registered: 4-2001
| | Posted on Sunday, July 13, 2003 - 12:32 am: | |
Driving yesterday with parking lights on, I noticed the car was running slightly warm. I was a little concerned but figured since it was warm outside, it was no biggie. Well, I get home and discover that the temp was fine, it was the guage that was off. When I parked and turned the lights off, the temp guage went down to normal!
It seems that by turning the lights on and off, I can change the readings on my guages (gas, temp and oil pressure) by about 10%.
I'm sure it's just the sign of a nearly 20 year old car, but kinda strange, nevertheless. I don't know why I never noticed it before...I guess mostly cause I don't drive at night that much.
Thoughts? |