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Discussion Starter #1
Got glhs 116 runnin after 20 years of sitting. It runs pretty decent at that. The issue I'm having is while sitting at idle the power loss light flickers. If the radiator fan kicks on it stays constant till the fan cycles off. With the lights on or the hvac blower on it will also stay on constantly. With lights and the hvac blower on high the voltage drops to 12.5 or so. The voltage hangs out there and will not recover. The voltage at the field terminals under load is 10 volts. At Wot it will also throw the power loss light then go away once you let off. Had the alternator tested at an auto parts store and they say it's good for what it's worth. The battery is new. I don't have much information on the car as the po died. I'm thinking the stock alternator just isn't cutting the mustard anymore but would like to know if I should check anything else. Rather not throw parts at it. Thanks brandon
 

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Got glhs 116 runnin after 20 years of sitting. It runs pretty decent at that. The issue I'm having is while sitting at idle the power loss light flickers. If the radiator fan kicks on it stays constant till the fan cycles off. With the lights on or the hvac blower on it will also stay on constantly. With lights and the hvac blower on high the voltage drops to 12.5 or so. The voltage hangs out there and will not recover. The voltage at the field terminals under load is 10 volts. At Wot it will also throw the power loss light then go away once you let off. Had the alternator tested at an auto parts store and they say it's good for what it's worth. The battery is new. I don't have much information on the car as the po died. I'm thinking the stock alternator just isn't cutting the mustard anymore but would like to know if I should check anything else. Rather not throw parts at it. Thanks brandon
You might want to check all the ground connections at the block, the negative batt. terminal and also the connections at the power loss light itself.
You can buy a brush kit for the alternator and replace them.
They wear out over time and cause low voltage.
The stock Alt. is only 78 amps and is the minimum.

Try this:
With the car running, turn on the A/C.
If the engine dies suddenly, you have a ground problem.
 

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Discussion Starter #3
You might want to check all the ground connections at the block, the negative batt. terminal and also the connections at the power loss light itself.
You can buy a brush kit for the alternator and replace them.
They wear out over time and cause low voltage.
The stock Alt. is only 78 amps and is the minimum.

Try this:
With the car running, turn on the A/C.
If the engine dies suddenly, you have a ground problem.
Ac compressor was removed so that isn't an option unfortunately
 

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At 12.5 volts there is obviously a charging system issue, the question however would be...
Are the charging system issue and the power loss lamp flickering/illuminating related and if so which is creating the issue.

1)As already stated check all grounds including the main controller ground at the fuel rail and the - battery cable to block.
ELECTRICAL- Main Controller Ground 84-89.jpg

2)Verify ALL fuses have power in and power out, a blown fuse may cause a condition of stray voltage where the currents normal path to ground is impeded so it looks for an alternate path, if it finds one components/lights that should not be on will be.

3)Will the system allow you to retrieve fault codes and if so are there any stored in memory?
 

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Discussion Starter #6
At 12.5 volts there is obviously a charging system issue, the question however would be...
Are the charging system issue and the power loss lamp flickering/illuminating related and if so which is creating the issue.

1)As already stated check all grounds including the main controller ground at the fuel rail and the - battery cable to block.
View attachment 272666

2)Verify ALL fuses have power in and power out, a blown fuse may cause a condition of stray voltage where the currents normal path to ground is impeded so it looks for an alternate path, if it finds one components/lights that should not be on will be.

3)Will the system allow you to retrieve fault codes and if so are there any stored in memory?
System has not thrown a code. Had a dead battery for 20 years and not sure if I just need to drive it more or not. It says 55 and that’s it. As far as the power loss light and the alternator issue bein related that’s just an assumption at this point. When Accesories are turned on the light is steady with them off it flickers at idle and goes away with some throttle till wot where it will come on again. I will dig into the grounds and such. And check all fuses.
 

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Discussion Starter #7
Nothing to update yet but plan on getting in the garage this weekend. Did order a nipedenso alternator to do an upgrade and an 89 turbo mini wiring harness to make work with it as well. Ill report back when i get a chance to get into the garage hopefully this weekend
 

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Nothing to update yet but plan on getting in the garage this weekend. Did order a nipedenso alternator to do an upgrade and an 89 turbo mini wiring harness to make work with it as well. Ill report back when i get a chance to get into the garage hopefully this weekend
I did the same with '87 GLHS 0956.
I had the harness, and bracket changed and added the 90 amp 'Denso alternator.
Never a fluctuation or drain on the system again,
and the headlights were a lot brighter.
 

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What does the power lose light look like? I am just curious.
 

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Discussion Starter #11
Update. Started the alternator upgrade which ended up doing a ton of wiring from scratch which isn't a bad thing. Fired it up last night and it was charging at 14.6 no matter how much load i put on the alternator and it didn't seem to miss a beat. When i put a load on the car it will momentarily flash the power loss light then immediately go away. Side note i replaced all the lights in the cluster with led bulbs and im wondering if that one should have a standard bulb and it may be messing with the circuit. Or im thinking to much into it. Thoughts?
View attachment 273739
 

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Nothing to update yet but plan on getting in the garage this weekend. Did order a nipedenso alternator to do an upgrade and an 89 turbo mini wiring harness to make work with it as well. Ill report back when i get a chance to get into the garage hopefully this weekend
If you ordered the 90 amp Denso, you're going to love it.
Plenty of power for All the accessories and bright headlamps too.
 

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What controllers and wiring are in this car?
Will the CEL flash codes and if so are any codes stored?
What is now controlling the charging system, LM/PM or an external voltage regulator?
 

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Discussion Starter #17
Im wiring one relay for my water to air intercooler pump and then im wiring another for the wideband and any other gauges i wanna run nothing crazy at this point. The stock lm pm is still controlling everything i just redid all the associated wiring when i did the upgraded alternator. The main power wire and ground wires were both coroded like crazy and insulation cracked so i just started over with alot of it. I added some grounds off the main ground for the things im gonna add and also 2 positive leads too to head into the fuse panel and back out. As far as coded i dont have anything other than 12 and 55 currently. The car would sit and idle no power loss light. Any load id put on it would trigger the cell. Like turn lights on or turn the blower on for the heat. Now i can turn them all on and the light will only flash on at that moment when i turn it on then go away. The car also would flash the cell at wide open throttle but i haven't taken it for a spin since. I still wanna check continuity with all grounds and such yet and maybe just change the bulb maybe it doesn't like the led bulb
 

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I have to look at the wiring to see exactly what controls the ground side of the CEL and exactly where power comes from.
Does the light only do this with the key in the "start" position?
As far as the LED being the cause, IDK.
 

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Discussion Starter #19
I have to look at the wiring to see exactly what controls the ground side of the CEL and exactly where power comes from.
Does the light only do this with the key in the "start" position?
As far as the LED being the cause, IDK.
When in start before starting the car the power light cycles as it should. After started it does the funky stuff. At idle sometimes it looks as its dimly lit but not sure if that's light bleeding from something else or not. Then when you turn a load on it will briefly flash and then shut off once the alt reacts.
 

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All sounds like a ground issue or stray voltage issue.

Have you verified ALL fuses are good?
A blown fuse can create a stray voltage issue if the current for that circuit finds another path to ground.
 
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