I should start with a hearty thank you! This is my first post, but I've spent a lot of time reading here and learning from you all over the last several years. I've searched the forum and I'm stumped.
Vehicle: '97 with the 4.0 and a 5 spd. (not an export)
Primary Problem: No headlights; no power to low beam, High beam reads continuity to ground from the combination switch harness to the harness on the other side of the firewall. I assume the problem is in the dash.
Repairs I've tried already: replaced headlight switch; replaced combination switch, checked fuses behind glove box and power distribution center; disconnected splices on the headlight output wires from the headlight switch.
Observations:
Sorry for such a long first post. I tried to include everything that I know in the first post. Thanks in advance to anyone willing to help me reason through this. I really appreciate it.
Vehicle: '97 with the 4.0 and a 5 spd. (not an export)
Primary Problem: No headlights; no power to low beam, High beam reads continuity to ground from the combination switch harness to the harness on the other side of the firewall. I assume the problem is in the dash.
Repairs I've tried already: replaced headlight switch; replaced combination switch, checked fuses behind glove box and power distribution center; disconnected splices on the headlight output wires from the headlight switch.
Observations:
- No continuity to ground from firewall harness to headlights on high beam wire. problem is in front of the firewall harness.
- Wire colors appear to be different than some of the diagrams I've seen here and elsewhere. ie violet/wht is low beam power wire, Orange/red is high beam from combination switch, but it sure looks solid red at the firewall harness.
- The harness that connects to the combination switch is black plastic, not gray.
- My son reported sporadic flickering of the headlights and that they would randomly shut off for a few seconds and come back on, I was never able to reproduce this before total failure
- The high beam indicator in the dash turned on for just a minute early in the process of fixing this, but it has not turned on again since.
- Blinkers, marker lights, tail lights, dimming of instrument panel, dome light, all work normally. Everything powered by the headlight and combi switch works except for headlights.
- (I'm guessing this is where the problem lies) Previous owner tapped the headlight outputs on the headlight switch and several other wires I've not yet identified under the steering column. I assume that he installed an alarm or theft deterrent device, and the taps from the headlight switch were running some aux lighting that is no longer there. (I've disconnected the wires from the headlight switch with no change)
- Where does the high beam wire go from the combi harness to the firewall harness? Does it power the indicator in the instrument cluster? Does it go to the PDC and back into the cab to do so?
- I'm no electrician, can someone explain how I'm getting continuity to ground and power from the headlight switch at the same time? I'd expect that short to have blown one of those fuses.
- The high beam is grounded, but the low beam is not. I'm not getting power to the low beam side at the firewall harness either. Are these independent from one another? Should I expect the low beam to work if the high beam is not?
- Is there something stupid easy here that I'm not looking at, or should I start tearing into the harness to chase the high beam wire?
Sorry for such a long first post. I tried to include everything that I know in the first post. Thanks in advance to anyone willing to help me reason through this. I really appreciate it.
