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On my M1028, I have flickering headlights (brighter than normal) and the volt meter spikes. When it does spike, it flickers into the overcharged side of meter, well into the red.
The problem is intermittent and does not happen every time the vehicle is running. I have seen the volt meter spike when the headlights are not on and I have seen it do it at idle, though it is predominantly when driving down the road. Occasionally, the truck will run for 20 minutes without it doing this, then have the issue for a few minutes, then be fine for the rest of the trip. The volt meter spiking issue can happen when the headlights and dash lights are turned off. The bright lights do still work, and get brighter yet when it flickers.
I have not been able to put a multimeter to the either alternator or batteries while the truck is running since it started having this issue.
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A bit of maintenance history -
I have done the Doghead relay mod.
Recently, the truck would not start. Jumping the rear battery (GEN2) I was able to get the truck started again and got home. GEN1 alternator and battery were reading 14.6v when running and GEN2 was reading 11.something volts. The GEN2 light had never worked, and I came to find out that the GEN2 diode was missing as well. The GEN2 alternator tested bad, and turned out to have a bad rotor, so I put a new GEN2 alternator in and the truck. I also added a new GEN2 diode. While I had the dash apart, I cleaned all the contacts on the in-dash "electrical membrane" and replaced all the in-dash bulbs. Having replaced the GEN2 alternator and cleaning all the electrical contacts, it was very nice to see all the dash lights working. The GEN1, GEN2, and oil pressure lights all came on when putting the key in the ignition which was something I had yet to see with this truck.
Everything seemed to work for a while, but now the dash illumination lights don't function. The left turn signal light stays on solid, but flashes when the signal is turned on. The bright lights indicator is on when the headlights are on the lower setting and off when the headlights are set to bright. The bright lights indicator also blinks opposite the left hand turn signal indicator light.
The fuel gauge now drops to empty when the dash lights are turned on. The fuel gauge has never worked correctly either, usually reading full until about 1/2 a tank, where it would drop at twice the normal rate. So when it started moving, I knew I had 1/2 a tank left.
The right front forward facing marker and right front side facing marker lights do not function. Both bulbs are new, and both turn signal portions of the light work, although they blink at a slower rate than the left side does. The in-dash turn signal indicator light does not work. I don't recall if the right side indicator lights up when the hazard lights are on.
The headlights flickering and the volt meter spiking did happen before I "fixed" the GEN2 problem as well, but I believe they went dimmer and the meter dropped into the red on the undercharged side, but I am not certain of that.
---
I can do many things, but an electrician I am not. I am, however, learning.
My inclination is that I might have a bad in-dash headlight switch, but I feel that I should fix the marker light issue before anything else...
What do I need to do first to determine what issues I am having?
Any help or suggestions are appreciated. Sorry for writing a book here, but I figure more information may yield a more productive answer.
The problem is intermittent and does not happen every time the vehicle is running. I have seen the volt meter spike when the headlights are not on and I have seen it do it at idle, though it is predominantly when driving down the road. Occasionally, the truck will run for 20 minutes without it doing this, then have the issue for a few minutes, then be fine for the rest of the trip. The volt meter spiking issue can happen when the headlights and dash lights are turned off. The bright lights do still work, and get brighter yet when it flickers.
I have not been able to put a multimeter to the either alternator or batteries while the truck is running since it started having this issue.
---
A bit of maintenance history -
I have done the Doghead relay mod.
Recently, the truck would not start. Jumping the rear battery (GEN2) I was able to get the truck started again and got home. GEN1 alternator and battery were reading 14.6v when running and GEN2 was reading 11.something volts. The GEN2 light had never worked, and I came to find out that the GEN2 diode was missing as well. The GEN2 alternator tested bad, and turned out to have a bad rotor, so I put a new GEN2 alternator in and the truck. I also added a new GEN2 diode. While I had the dash apart, I cleaned all the contacts on the in-dash "electrical membrane" and replaced all the in-dash bulbs. Having replaced the GEN2 alternator and cleaning all the electrical contacts, it was very nice to see all the dash lights working. The GEN1, GEN2, and oil pressure lights all came on when putting the key in the ignition which was something I had yet to see with this truck.
Everything seemed to work for a while, but now the dash illumination lights don't function. The left turn signal light stays on solid, but flashes when the signal is turned on. The bright lights indicator is on when the headlights are on the lower setting and off when the headlights are set to bright. The bright lights indicator also blinks opposite the left hand turn signal indicator light.
The fuel gauge now drops to empty when the dash lights are turned on. The fuel gauge has never worked correctly either, usually reading full until about 1/2 a tank, where it would drop at twice the normal rate. So when it started moving, I knew I had 1/2 a tank left.
The right front forward facing marker and right front side facing marker lights do not function. Both bulbs are new, and both turn signal portions of the light work, although they blink at a slower rate than the left side does. The in-dash turn signal indicator light does not work. I don't recall if the right side indicator lights up when the hazard lights are on.
The headlights flickering and the volt meter spiking did happen before I "fixed" the GEN2 problem as well, but I believe they went dimmer and the meter dropped into the red on the undercharged side, but I am not certain of that.
---
I can do many things, but an electrician I am not. I am, however, learning.
My inclination is that I might have a bad in-dash headlight switch, but I feel that I should fix the marker light issue before anything else...
What do I need to do first to determine what issues I am having?
Any help or suggestions are appreciated. Sorry for writing a book here, but I figure more information may yield a more productive answer.
