 Weird Electrical Happenings-Part 1, ...turning headlight knob effects full gauge |
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| 7TPorsh |
 Aug 20 2010, 09:13 AM
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7T Porsh  Group: Members Posts: 2,691 Joined: 27-March 06 From: Glendale Ca Member No.: 5,782 Region Association: Southern California 
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I have a bunch of little weird electrical things going on...so i'll attack one at a time:
The fuel gauge (stock combo gauge) moves as follows under different conditions: - Ignition off/headlights on- turning headlight knob up makes fuel gauge go from empty to full; turning down go back to empty. - Ignition on/headlights on- fuel gauge show reading...turning knob up increases the reading on the fuel gauge by 1/4 tank; turning down decreases...so 1/4 fluctuation in the fuel gauge depending on how the headlight knob is turned. Tend to think the full bright on the headlights translates to a closer fuel reading. But why? is the power source for the fuel gauge incorrect? I checked the schematic, but it looks like a Lucas engineer designed the wiring for the combo gauge. |
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| realred914 |
Aug 20 2010, 10:36 AM
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Senior Member Group: Retired Members Posts: 1,086 Joined: 1-April 10 From: california Member No.: 11,541 Region Association: None |
QUOTE(7TPorsh @ Aug 20 2010, 08:13 AM)  I have a bunch of little weird electrical things going on...so i'll attack one at a time: The fuel gauge (stock combo gauge) moves as follows under different conditions: - Ignition off/headlights on- turning headlight knob up makes fuel gauge go from empty to full; turning down go back to empty. - Ignition on/headlights on- fuel gauge show reading...turning knob up increases the reading on the fuel gauge by 1/4 tank; turning down decreases...so 1/4 fluctuation in the fuel gauge depending on how the headlight knob is turned. Tend to think the full bright on the headlights translates to a closer fuel reading. But why? is the power source for the fuel gauge incorrect? I checked the schematic, but it looks like a Lucas engineer designed the wiring for the combo gauge. sound slike you have a misswire probelm. disconect the battery so as to not short anythign out, and get under the dash and trace the wires. seem like the full gage is being supplyed powewr that is meant for the dashboard lights (which are dimmable). do you have a electric diagram, like from the haynes book? if so, use that as a cross check for teh wires, pay close attention tot eh wires on teh back of the fuel gage, and the wires that power the dash lights (all the dash lights should be daisey chained together) the fuel gage should have a black and a green wire (if I read the small print on teh diagram right) thesetwo wires come from teh gas tank sendor there is a third wire on teh gage, a red and white one, for power good luck |
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Posts in this topic
7TPorsh Weird Electrical Happenings-Part 1 Aug 20 2010, 09:13 AM
Cap'n Krusty Check your grounds, then use the wiring diagram to... Aug 20 2010, 09:29 AM Tom Did this just start after you made some repairs/mo... Aug 20 2010, 11:33 AM 7TPorsh I think it has always done this and I just discove... Aug 20 2010, 11:37 AM Tom Since it has been sitting for a while, I would exp... Aug 20 2010, 12:05 PM kg6dxn Electrical systems will do strange things when a g... Aug 20 2010, 01:07 PM Tom Mike,
Very well put. Exactly what I was thinki... Aug 20 2010, 01:11 PM 7TPorsh Where are the ground connections points? Diagram s... Aug 20 2010, 01:49 PM
kg6dxn
Where are the ground connections points? Diagram ... Aug 20 2010, 02:58 PM 7TPorsh Well i checked around...behind the front trunk pul... Aug 27 2010, 12:06 PM realred914
Well i checked around...behind the front trunk pu... Aug 27 2010, 12:42 PM kg6dxn There is a dash light that illuminates with the pa... Aug 27 2010, 01:07 PM 7TPorsh
There is a dash light that illuminates with the p... Aug 27 2010, 02:00 PM kg6dxn
There is a dash light that illuminates with the ... Aug 27 2010, 02:44 PM realred914
There is a dash light that illuminates with the ... Aug 27 2010, 02:53 PM |
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