For what it's worth, by switching wires around on the left side of the fuse box (facing car) I was able to re-activate the OverDrive function. I am almost back to baseline, except my turn signals and fuel/temp/oil pressure gauges will only work when I turn on the headlamp running light switch (either with or w/o the headlamps). They don't work with just the one-sided parking light on as expected I guess. So the car actually functions normally again if I always drive with running lights on-probably not a bad idea, but I'd like all this to work properly of course. More fiddling to come later I suspect. Clearly the PO did some fancy electrical work somewhere!
For a final (hopefully) followup, after working with the circuit diagram more I finally have my wiring connected with the correct color code. Someone had used Red wire for the ignition circuit instead of the proper White wire. I realized I could easily check this by using a voltmeter at the fuse box. The top (#1) Brown wire is always 'hot' reading 12 volts, but terminal #3 (White) should only read 12 volts when the ignition is switched on; and terminal #5 (Red) should only read 12 volts when the parking lights are turned on. So I put proper colors on the wires and hooked up per WSM diagram and all works well again. Hallelujah!
Post by Phil Nottingham on Sept 26, 2018 17:41:43 GMT
So it was a PO mod?
That is how it should be - the relay incorporates a resister which is essential. This could have burnt out. You can bypass everything to see how things work but ensure the overdrive is never ever engaged in reverse and driven otherwise its toast