lnevill
Well-known member
- Joined
- Jun 25, 2013
- Messages
- 64
I started a post last week on a problem I was having with Bonnie and Clyde's Oil Pressure idiot light. Now that I have this issue resolved and understood, I thought it would be best to re-post and clear up some of the misleading information I put in that post!!
1. I was not able to find a schematic from Ford for the tach dash wiring. There is a supplement that shows how to wire in the tach itself (hot wire in series with coil), but nothing on the Alt and OP idiot lights.
2. The schematic for the non-tach car does not help (this is where I went wrong). This schematic shows the OP power source as the constant voltage regulator. It is for a guage, but it is not for an idiot light. As RVRTRASH (Steve) tried to point out in the previous post, the source of the power for the OP light is 12v, and in fact is the same wire that feeds the dual brake warning light.
3. The wire colors stamped by each socket on the back of the dash itself are the best source of knowing which wires go where. When comparing to the non-tach schematic, I thought wires had been swapped when the harness was restored, but the colors match what is stamped on the panel.
Here are the wire colors for the tach dash harness:
Oil Pressure hot (12v) = Red/Yellow
Oil Pressure sender = White/Red
Alt hot (12v) = Black/Green
Alt sender = Yellow/black
Brake hot (12v) = Red/Yellow
Brake sender = Violet/white
My constant voltage regulator was indeed fried, but I don't think it had anything to do with this issue. I found the 12v lead that feeds the red/yellow wire to be broken at the connector. Fixed that, replaced the VR and all is good!
Thanks,
Lee
1. I was not able to find a schematic from Ford for the tach dash wiring. There is a supplement that shows how to wire in the tach itself (hot wire in series with coil), but nothing on the Alt and OP idiot lights.
2. The schematic for the non-tach car does not help (this is where I went wrong). This schematic shows the OP power source as the constant voltage regulator. It is for a guage, but it is not for an idiot light. As RVRTRASH (Steve) tried to point out in the previous post, the source of the power for the OP light is 12v, and in fact is the same wire that feeds the dual brake warning light.
3. The wire colors stamped by each socket on the back of the dash itself are the best source of knowing which wires go where. When comparing to the non-tach schematic, I thought wires had been swapped when the harness was restored, but the colors match what is stamped on the panel.
Here are the wire colors for the tach dash harness:
Oil Pressure hot (12v) = Red/Yellow
Oil Pressure sender = White/Red
Alt hot (12v) = Black/Green
Alt sender = Yellow/black
Brake hot (12v) = Red/Yellow
Brake sender = Violet/white
My constant voltage regulator was indeed fried, but I don't think it had anything to do with this issue. I found the 12v lead that feeds the red/yellow wire to be broken at the connector. Fixed that, replaced the VR and all is good!
Thanks,
Lee