Idiot light failure? What controls the idiot lights?
07-06-09, 08:01 AM
#1
Right near Malloy
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Idiot light failure? What controls the idiot lights?
When I got my 1986 GXL, I noticed that the clock didn't work and the idiot lights didn't all come on when I turned the key on with the engine off.
I went and unplugged the low coolant sensor. Sure enough, no light or buzzer.
Popped my idiot cluster into a 1988 GTU and it worked like it should. So my cluster is good. What else should I look into?
BTW, I already retouched all the solder joints on the connector on the back. At least my clock works now...
I went and unplugged the low coolant sensor. Sure enough, no light or buzzer.
Popped my idiot cluster into a 1988 GTU and it worked like it should. So my cluster is good. What else should I look into?
BTW, I already retouched all the solder joints on the connector on the back. At least my clock works now...
Last edited by Pele; 07-06-09 at 08:21 AM.
07-06-09, 11:51 AM
#3
Rotary Freak
Key ON engine OFF. Pull the small plug off the alternator. Put the WHITE/BLACK wire to ground . When you do that you should be able to hear the alternator relay inside the CPU click. When it clicks, all the warning lights in the warning unit should come on.
If that act does not turn all the warning lights on, then get apiece of wire and bare it at each end. Pull the top plug off the CPU. Put one end of your bare wire to the Yellow/Blue wire in the connector. With key ON, engine OFF and the OTHER end of that new wire put to gnd, all the warning light should come on. see jpg
If you put the black/white wire of the small plug on the alt to gnd, you've just blown the ENGINE fuse. Replace same.
IF the warning lights only come on when you put a gnd to the yellow/blue wire on the CPU's upper plug, then either the alt relay inside the CPU is bad...............or the gnd wire that goes to the contacts for the alt relay is not grounded............or the wire is open b/t the alt small plug and the CPU.
The way things are supposed to work is like this. When the alt is not turning, the W/B wire gets a ground signal put on it thru the alternators field windings. That gnd then gets put on the alt relay in the CPU. That causes the alt relay to pull in and its contacts to *make*. One side of the contacts is a premanent ground. The other contact it mates with goes to the warning light assy and puts a gnd on all the lights in the warngin light assy. There is already power on the other side of each light, so now all the lights come on.
Lets say you put a gnd on the White/Black wire with key on engine off and all the warning lights DID come on. Then the alternator is bad to some extent. The regulator has been damaged and needs to be replaced. They cost about twenty five bucks and take some slight soldering skill to replace inside the alternator.
If that act does not turn all the warning lights on, then get apiece of wire and bare it at each end. Pull the top plug off the CPU. Put one end of your bare wire to the Yellow/Blue wire in the connector. With key ON, engine OFF and the OTHER end of that new wire put to gnd, all the warning light should come on. see jpg
If you put the black/white wire of the small plug on the alt to gnd, you've just blown the ENGINE fuse. Replace same.
IF the warning lights only come on when you put a gnd to the yellow/blue wire on the CPU's upper plug, then either the alt relay inside the CPU is bad...............or the gnd wire that goes to the contacts for the alt relay is not grounded............or the wire is open b/t the alt small plug and the CPU.
The way things are supposed to work is like this. When the alt is not turning, the W/B wire gets a ground signal put on it thru the alternators field windings. That gnd then gets put on the alt relay in the CPU. That causes the alt relay to pull in and its contacts to *make*. One side of the contacts is a premanent ground. The other contact it mates with goes to the warning light assy and puts a gnd on all the lights in the warngin light assy. There is already power on the other side of each light, so now all the lights come on.
Lets say you put a gnd on the White/Black wire with key on engine off and all the warning lights DID come on. Then the alternator is bad to some extent. The regulator has been damaged and needs to be replaced. They cost about twenty five bucks and take some slight soldering skill to replace inside the alternator.
