Warning lights stay on while running
Thread Starter
Joined: Aug 2001
Posts: 2,991
Likes: 34
From: Deadmonds, WA
Warning lights stay on while running
I got my 85 GS to idle but all the warning lights remain on while running. I think I remember that happening when I lost an alternator belt on my 83 forever ago
But the alternator belt is still good on this one.
Any advice?
But the alternator belt is still good on this one.
Any advice?
ancient wizard...
Joined: Sep 2014
Posts: 2,335
Likes: 262
From: Maryland
Yep,if that fuse is good,go to the connector on the back of alternator and be sure it's seated. To test the warning light circuit,remove connector on alternator and all warning lights should go out,if so it's one of two things.
Either the alternator is not charging or the exciter wire from ignition switch is not energizing the voltage regulator to initiate charging. You have to determine which it is.
This is a good use for the multimeter I referenced in your no start thread.
Start by checking battery voltage with engine off,should be @12.6 volts. Is it? Start car and check voltage at battery now,if charging, voltage should be at least 13.5-14.2 volts.
If not alternator is not charging and is why all warning lights are on.
Remove connector from back of alternator, turn key on and with multimeter ground the black test lead to engine and probe back side of terminals in connector.
One terminal will have approximate battery voltage and this is the exciter wire from ignition switch to regulator in alternator. I think it's the white/black tracer wire. The other wire in the connector you already know is good because all the warning lights are illuminated.
When you turn the key on to the run position,all warning lights will illuminate and stay lit with the exception of seat belt warning light which is grounded through a timer and will turn off in 5 seconds. This is referred to as a bulb check.
All the warning lights receive voltage through the ignition switch and ground through alternator rotor. When engine is started and alternator begins to turn and generate voltage the rotor is energized and no longer grounded and warning lights go out.
Each different warning light is grounded through a switch or sensor dependent on circuit it's dedicated to.
So,if all warning lights are on, either the alternator is not turning(no belt) there is no regulator exciter voltage coming to alternator from ignition switch or alternator is defective.
Post back findings to help next person searching threads for answer to same symptoms.
Either the alternator is not charging or the exciter wire from ignition switch is not energizing the voltage regulator to initiate charging. You have to determine which it is.
This is a good use for the multimeter I referenced in your no start thread.
Start by checking battery voltage with engine off,should be @12.6 volts. Is it? Start car and check voltage at battery now,if charging, voltage should be at least 13.5-14.2 volts.
If not alternator is not charging and is why all warning lights are on.
Remove connector from back of alternator, turn key on and with multimeter ground the black test lead to engine and probe back side of terminals in connector.
One terminal will have approximate battery voltage and this is the exciter wire from ignition switch to regulator in alternator. I think it's the white/black tracer wire. The other wire in the connector you already know is good because all the warning lights are illuminated.
When you turn the key on to the run position,all warning lights will illuminate and stay lit with the exception of seat belt warning light which is grounded through a timer and will turn off in 5 seconds. This is referred to as a bulb check.
All the warning lights receive voltage through the ignition switch and ground through alternator rotor. When engine is started and alternator begins to turn and generate voltage the rotor is energized and no longer grounded and warning lights go out.
Each different warning light is grounded through a switch or sensor dependent on circuit it's dedicated to.
So,if all warning lights are on, either the alternator is not turning(no belt) there is no regulator exciter voltage coming to alternator from ignition switch or alternator is defective.
Post back findings to help next person searching threads for answer to same symptoms.
Last edited by GSLSEforme; Dec 6, 2018 at 10:25 PM.
Thread Starter
Joined: Aug 2001
Posts: 2,991
Likes: 34
From: Deadmonds, WA
Took a look at the wiring diagram and put some scrutiny on my wiring delete, pretty sure I have one of the wires off the alternator connected incorrectly. Gotta chase some loom.
The choke/check relay (located near the brake booster on LHD cars) is also part of the "bulb check" circuit. It's not a common failure point but if you are certain all the other connections are good it's possible the relay is stuck on or the cable between the relay and alternator is grounding out due to a failed jacket.
ancient wizard...
Joined: Sep 2014
Posts: 2,335
Likes: 262
From: Maryland
A suggestion here,check simple,basic stuff before diving in to wiring.
Is the alternator charging the battery? If not work from the alternator backwards to wiring harness. Rule out simple stuff 1st before you start chasing your tail.
Remember KISS keep it simple,stupid.
Alternator needs a drive belt to turn it,has to be grounded,needs its output connected to main fuse link in car and needs an exciter voltage to the regulator in alternator to initiate charging.
Is the alternator charging the battery? If not work from the alternator backwards to wiring harness. Rule out simple stuff 1st before you start chasing your tail.
Remember KISS keep it simple,stupid.
Alternator needs a drive belt to turn it,has to be grounded,needs its output connected to main fuse link in car and needs an exciter voltage to the regulator in alternator to initiate charging.
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Thread Starter
Joined: Aug 2001
Posts: 2,991
Likes: 34
From: Deadmonds, WA
OK got it sorted, pretty much. I found the fault but haven't implemented the permanent fix. It was my fault for misreading the wiring diagram the first time. I had the BW wire from the back of the alt going to ground instead of going to the big X...-07? connector on the right hand side of the engine bay near the firewall. That is part of the circuit that energizes the switch in the C&C relay. I need to get a set of tiny male spade connectors and I can complete the fix with a tidy wiring job.
The wiring in this car is super simplified
At the moment it's running on stock ignition, charging, and C&C relay circuit. Then I did an engine harness delete and only retained the sensor wires that feed the dash gauges.
The wiring in this car is super simplified
At the moment it's running on stock ignition, charging, and C&C relay circuit. Then I did an engine harness delete and only retained the sensor wires that feed the dash gauges.
Last edited by cpt_gloval; Dec 8, 2018 at 07:47 PM.
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