I have been reading up on head lights and how they are routed through relays and how there seems to be a number of variations, on wiring, variations either made by the the PO, a mechanic trying to make it work, or made by the manufacturer depending on the year of the GT. I have spent three four hour afternoons lying on my back looking up at this fuse box, testing connections - trying to figure it out, and would appreciate some help if this sounds like something you have been through. So these are the facts:
- Head lights are too dim on the low setting - I would guess around 50 % too dim
- I replaced headlight wiring harness was with a new wiring harness in 2000 - not a 70 model as it had a few more wires than the one I was replacing - the car has been in a garage and has only been driven 2700 mile since that time although I believe the dim head lights go way back, I think back 39 years or so - when I replaced the head light wiring harness I assumed it would be cured
- I have cleaned the 4 main contacts on the fuse box so they now register the same as a direct read from the battery/ starter solenoid so plenty of power to that point 12.3
- There is an anomaly in the relay wiring - Looking at the instruction for relay testing - D which is on the 7 prong relay is suppose to be "white/yellow striped wire # 87 this wire splits which carry 7-prong relay output power to 5 prong relay inputs labeled E " - My GT has no wire attached to that prong that connection is plugged into the fuse box, laying on your back looking up, closest to front of car second from the left/ passenger side front - don't think this is part of the issue but not sure - this prong with wire attached and lights on reads 4.15 volts on the multi-meter - to my knowledge the car came like this and again I don't think that is part of the issue
- All of the other prongs read around 9.5 on both relays, while the battery and the 4 main fusebox connections were at 12.3 - keep in mind that I have been doing a lot of testing over the past three days do that is why the battery is low, as it is new - that is the ones that are supposed to have power
- The gauge lights work only on the speedometer and the tach - the amp meter idiot lights come on when car is turned on but not the gauge lights on the three small gauges
- High beam low beam switch is working, blinkers, everything else - the passenger blinker indicator does double blink but still works fine
- So just a thought, with the lights on the 9.5 on the relays would that just be a function of the power drain from 12.3 to 9.5 or should it read 12.3 as well. Do I need to retest this with the car running however in the past lights were also dim with the car running
- I guess one possibility is the relay needs to be replaced but it does past the test - seems odd that the voltage is lower on all of the relay contacts except the one that is around 4.15