Last week I wrote that my high beams and wipers didn't work. Aye Roll replied that I should check the headlight relay and fuses. I did. There was some corrosion and I cleaned it up. No improvement.

On Thursday the horn quit working.

I've had an idle problem that would sometimes cause the engine to die. I was living with it. Late last week it was dying more frequently, and sometimes would die and only the oil pressure warning light would illuminate - not the row of lights you normally get.

When under the hood fiddling with the headlight relay, I noticed that the battery terminals were beginning to cake up with that white powdery residue quite heavily. I cleaned it all up this morning. The negative cable connector cleaned up but part of it looked like copper. Took the car for a 20 minute spin just now, and the negative cable connector is completely frosted over with whire residue again.

Obviously I have an electrical problem. I'm guessing something significant, potentially disabling, and possibly damaging to other components. Any suggestions about what it might be, or where to start looking?

Thanks.

PS. Fixed the idle problem by cleaning the throttle body.

I don't know if anyone has mentioned that the '86 model still has the poor wiring harness. The insulation degrades and strange electrical problem can result. On several of my 240s, including my '86 245, I replaced the electrical wires (2) which go down under the front of the engine. On the '86 I ran the red and black wires back along the passenger side fender then the firewall to the gray connector. I spliced them in the and cut the original wires loose. The rest of the harness still is working ok.

The problem you mention sound like the harness may be at fault.

When I get that white residue on the battery terminals I clean them up with a solution of baking soda,rinse, dry, and coat with a battery protective substance or silicone grease. I've also had stalling problems cause by a battery connector which was repaired by resoldering the connector (cheap fix).

After cleaning, wire-brushing, whatever, to the battery cables, it's best to coat them with some kind of grease to prevent oxidation.
There is a special dielectric grease sold to prevent corrosion in connectors (works great for headlight plugs especially) but other greases will work, like the silicone brake grease (Syl-Glide). Put something one there to prevent reoccurence of corrosion.
It's possible the battery is being overcharged and is making a mess while the car's running. This can be due to a shorted cell in the battery getting real hot, or an alternator that's overcharging. The small red wire from the alternator needs to be inspected- if it grounds out, it can turn the alternator on trying to make it charge 100%, and that'll burn out light bulbs and boil the battery dry. The wire can be inspected around the (filthy!) bottom crank pulley if you remove the splash pan below the engine- it might be gone anyway.

Did you check the wires around the relay? Take it off the fender and flip it over to inspect? I had, of all things, a broken bracket that held the coil and PS reservoir... the edge of that severed a wire for the high beams. If the light relay clicks on and off when you pull the stalk, the control wire is working, and either the bulbs are burnt out (not likely) or the relay is defective, or wiring to it has broken. Note that there's a second headlight relay by your left foot on the firewall- but if it goes out the entire headlight circuit won't work (parking lights will).
Good luck again!
--
Rob Bareiss, New London CT ::: '87 244DL/M47- 229K, 88 744GLE- 218K, 82 245T-181K Also responsible for the care and feeding of: 88 745GLE, 231K, 87 244DL, 239K, 88 245DL, 246K

My Friend,

AyeRoll is very knowledgable and I trust him implicitly; however, do you own a Bently Manual. In your situation, it might be the be $20-$40 you ever spent. It has wiring diagrams, relay locations, and electrical tests your can perform yourself.

As for your drama, I would first check the wiring the runs under the motor to the alternator. The battery connections are also important, and a good place to look as well. Make sure the cables are in good shape and clean. Fuse box -European fuses & holders need to be changed and cleaned- I have solved a couple of electrical problems this way.

You will need to search and destroy. May take awhile, so post back with any issues!

Shaka, Jon

Oh yeah, about forgot ... the high beam issue WAS a problem with the relay. Either it wasn't getting juice (although I've seen worse connectors still conduct) or some corrosion on the front end of the baseplate beneath the coil had shorted it. In any event, I cleaned it up best I could, put it back, and it works like a champ.

Thanks again, Aye Roll.

Everyone:

This is not quite the final report, but I have found a series of problems.

First, the plates visible through one of the battery fill holes was higher than the others, so I suspect it was swollen and possibly shorted. The battery was at least 7 yrs old, so I replaced it.

I hand-over-handed the alternator field and charging leads and except for some heat embrittled conduit didn't find any insulation breaches.

The horn went out when it's fuse burned. The fuse burned because the wiper motor failed - strong odor when I began to disassemble. By its looks it could be an original (206Kmis). I will replace tomorrow.

I will get a Bently manual and do some electrical health and welfare checks to be sure no more gremlins are hiding.

Thanks to Aye Roll, KarmaticLove, Dick in Falls Church, and Jim Holst for all your help.

Not sure, but my daughter's Saab had a similar problem at the battery terminal. I cleaned it up, and within days it was bad as before.
Appears that there was a crack at the terminal, letting the gases escape.
At any rate, I bought an Optimal battery and put it in last week. Checked today, and no corrosion.