I have a 1987 245, 5 speed, and I have an interesting problem: My alternator light on the cluster DOES NOT light up at any point, yet the car starts, runs, drives, and charges the battery properly. The voltage is correct (+or-13.1) coming out of the alternator, and at the battery which is less than two years old. Most importantly, it always starts right up, even on cold (below 40º) mornings after sitting all weekend. I under stand this should be impossible, as the alt light must be illuminated to close the circuit to charge. Is that correct?

Heres a bit of related history: I just replaced the timing belt, and in so doing discovered the big wire that goes from Starter to Alternator under the timing belt cover was broken through more than half the stranded wire. I was having some bizarre lights and radio problems, which I attributed to this. I replaced this wire entirely (same gauge and nice, big soldered and crimped connectors with heat shrink shields on the connectors) AND spliced the exciter wire (also frayed) from a point just over the starter over to the alternator. I also replaced the small wire that grounds the alternator to the block, which was almost in two as well as the block to firewall ground, which was 3/4 torn at the firewall connection. I also replaced the alternator, as it sounded like it was full of gravel, and just barely put out enough voltage. I would have just done the brushes, but it seemed as though some bearings were shot, so I just did the whole unit. It wasn't an original Bosch alternator, anyway.

Also, this car has had the entire problematic rotting wiring harness replaced with a new one. This was done in 2004, I bought the car from a Volvo mechanic in 2005 at a dealer who did it in the shop he worked in. All the insulation still looks good on the other bundle of wiring that runs to the passenger side to the ECU, which I re-routed over the top of the engine with the starter to alternator wire and exciter wire.

Finally, the amp light WAS lighting up before I did all this electrical work. I discovered the whole exciter wire thing when I made the mistake of running it without the cluster in, so i've always kept an eye on it since then. After I rerouted the big wire and fixed the frayed alt to block ground, all my electrical problems disappeared. Even the dome light started working properly again.

I have two questions for your consideration:

1) How can I trouble shoot this exciter wire thing more? Should I worry about it? I'm afraid the car is going to stop charging the battery and leave me stranded at some point...is it tricking me into trusting it?

2) Has anyone done this wiring/vacuum line re-routing before for the ECU? It seems almost like a better position for the wires, as long as they stay out of the exhaust manifold. Any suggestions for nice ways to tie them up and protect them from engine heat?

Thanks for any suggestions!

C