1994 Corolla electrical issues

#1
I have a great Corolla (1.8L DX Wagon) with a pesky intermittent electrical issue. Sometimes when I hit the brakes, or apply the hazards/turn signals, some variation of my headlights/dashlights/clock will dim, but of course, it only happens sometimes (and this only happens when the car is running). Additionally: when I'm sitting in park with the car running, or sitting in drive at a light, and I put on the hazards, the engine will start surging (this symptom is pretty consistent). I have never been stranded due to this issue, and the car has never not started. It's just really annoying, and kind of unsafe, as the headlights will completely go out momentarily and then return to original brightness (when the issue is happening of course).

I have been trying to fix this for quite some time now, with no success.

Here's what I've tried:

-Battery (was due for a new one anyway)
-Alternator
-I have located all ground straps from the kick panels (under the dash) forward, which seem to all be tight and intact
-I have tried swapping in a different relay integration (from the junkyard)
-I even tried swapping in a new ECU (again, jy)
(the reason I tried the above is that the issue seems to go away for a short period pretty consistently after I have disconnected and reconnected the battery)
-I have tried individually pulling fuses from the driver's side junction block to see if removing any circuit made the issue go away (no success).
- All fuses look intact, and all electrical systems are working.

So I'm just completely stumped and discouraged. What should I look at next? Is there some electronic component I have overlooked somewhere? I didn't test any relays because I was not sure that a faulty relay would cause an issue like this, am I wrong about that? Is there some other voltage regulator in my car that I don't know about?

Thanks for any help you may have.
 
#2
I have a great Corolla (1.8L DX Wagon) with a pesky intermittent electrical issue. Sometimes when I hit the brakes, or apply the hazards/turn signals, some variation of my headlights/dashlights/clock will dim, but of course, it only happens sometimes (and this only happens when the car is running). Additionally: when I'm sitting in park with the car running, or sitting in drive at a light, and I put on the hazards, the engine will start surging (this symptom is pretty consistent). I have never been stranded due to this issue, and the car has never not started. It's just really annoying, and kind of unsafe, as the headlights will completely go out momentarily and then return to original brightness (when the issue is happening of course).

I have been trying to fix this for quite some time now, with no success.

Here's what I've tried:

-Battery (was due for a new one anyway)
-Alternator
-I have located all ground straps from the kick panels (under the dash) forward, which seem to all be tight and intact
-I have tried swapping in a different relay integration (from the junkyard)
-I even tried swapping in a new ECU (again, jy)
(the reason I tried the above is that the issue seems to go away for a short period pretty consistently after I have disconnected and reconnected the battery)
-I have tried individually pulling fuses from the driver's side junction block to see if removing any circuit made the issue go away (no success).
- All fuses look intact, and all electrical systems are working.

So I'm just completely stumped and discouraged. What should I look at next? Is there some electronic component I have overlooked somewhere? I didn't test any relays because I was not sure that a faulty relay would cause an issue like this, am I wrong about that? Is there some other voltage regulator in my car that I don't know about?

Thanks for any help you may have.
This could be a Case of a loose wire earthing off.
 
#3
Make sure you vehicle has the correct amperage alternator installed and I would also check wiring or relays for high resistance.
 
#4
See my post on speedo failure. I suspect a high resistance connection on the two multi pin plugs behind the speedo cluster. They have not been moved for many years.
 
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