Hi all,

I have got a very frustrating problem with my brick. It will start up but sometimes will die immediately after I turn on the lights. It will then not be able to restart for several more hours. Everything electrical dies for a couple of hours. Then it is able to start right back up. This happened to me once before when I hit the bright and dimmer switch. Any ideas what is going on? Thanks in advance. George

I just had the same problem with our '90 744 TI - it was in the 700/900 FAQ!

In my case, it was a bad ground in the left front fender where the ignition components reside.

Evidently there was not enough ground available, and the high beams hogged it all.

I cleaned the back of the power stage, found a bad pin in the connector to the thing that looks like 4 ballast resistors. I also cleaned the ground at the base of the car's ABS control box.

My favorite tech advised me to clean and apply dielectric grease to all grounds and connectors, adding a zip-tie to all connectors to hold them tight.

I am doing one per week so that if I have a problem, I'll know which one it is.
--
'96 855R, 95 855, '95 854, 90 744TI 377,000 miles on 7 bricks

One exception: no dielectric grease on the O2 sensor connector!
-Chris
--
Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf

Sounds like your alternator is not charging. You battery is probably good, since it is recharing a bit after sitting. It could just be the voltage regulator on the alternator. Take it to a reputable alternator shop and they will test it for nothing and can replace the regulator is required. I find they my local alternator shop charges no more for parts than Autozone.

When you car is running, put a volt meter (set at 12 volts dc) across the battery and see if you have more than 12 volts. If the alternator is charging you should have around 13.5 volts.

Gary

I'd also check the battery cables, paying particular attention to the ends where they enter the terminals. Any corrosion/breakdown (as evidenced by visible corrosion, broken wires, or warm insulation near the connector) in the wiring can eventually lead to the condition you describe - an intermittant complete loss of the entire electrical system. Also check the ground connections to the block & chassis, and the positive lead from the battery to the starter. If all of this checks out, and the alternator passes the test, crawl under the car & remove the belly pan. Look for insulation breakdown or signs of arcing in the harness that runs from the alternator to the starter. Saw a 740 burn because the loom cracked, then the insulation wore away shorting the positive lead to ground, at first just enough to stall the car once in a while but it got progressively worse, quickly...
-Chris

Do check the wiring: as you may know, '86 is in the bad insulation years. But this problem could even just be the battery cable connection to the battery, sometimes you can have just enough corrosion under the clamp to cause the problem but not be visible from the outside.

--
'81 GLT 245 W/245K; '83 DL 175K