Alan

Tim - Yes (61) is the Exciter circuit - your pin assignment is correct and the method is as you surmised.

Alan

85fortheDrive

April 3 tests...
DMM is hooked to H8 and ground.
0V with key out
1.8V with key turned to ignition point
14.3V while engine is running.

However, on the very FIRST start this evening, the voltage went high again. The gauge went way past the red zone and the DMM read 16, then 17, then 18.5V. So the exciter circuit followed that voltage.

No voltage flatline to report today, though.

Continued thanks.

Landseer

Now that sounds like an important observation!

6mil928

Alan

Humm - not so much.. I'm looking at this only for any indication that when the alternator stops generation the (61) circuit goes hard clamped to 0V.... anything else doesn't mean so much...

The fact that the (61) follows the output is behaviour as expected - it should track the output voltage - the regulator should stop it going so high... but it should ~ match the output voltage otherwise.

Alan

85fortheDrive

I kind of figured this. Before putting in the replacement alternator, I would like to see what happens if/when the voltage drops off. Preemptively, what would the implications be if the voltage dropped off both from the alternator and at the exciter circuit. Or, conversely, if the alternator voltage drops and the exciter circuit does NOT.

Elsewhere, please note Alan's inclusion of a "u" in the word behavior. For those who haven't met him, he is, like Roger Tyson, from across the pond. Thank God they've come over!

Alan

Tim - if the alternator stops generating it will be interesting to see if the exciter voltage is ~ 2v as you have seen in pre-start ignition on - which to me would say the alternator just stopped generating of its own accord OR if the output is almost exactly 0v - then I would suspect something in the (61) circuit is shorting to ground and causing the rotor field to collapse as a result. Alternatively it could be be ~12v which would suggest the brushes are not contacting the rotor slip rings properly.

Either way I can't see this being directly related to the high voltage condition...

85fortheDrive

April 4 report:

Took the car out for a six mile errand run this evening. No problems on the way to the store. In the store for 10 minutes. Weather is dry and 40's.

Started car in parking lot to no voltage. DMM, connected still to exciter circuit, read 10.10 volts. This is at least two volts below the battery output. Low voltage light did not illuminate on that start.

Turned off car and, upon restart, got normal voltage all the way home, with just one brief swell to 15.8V.

New alternator arrived today from Rog, but I'm not going to install it until all diagnostics are run with current equipment.

Suggestions?

Peace,
Tim

Landseer

I would probably take 20 minutes and remove the CE panel. Inspect the back of it, and every wire on every plug, for burnt insulation, strip away the wire wrap a few inches on wire distribution bundles behind the panel, and clean the grounds behind the panel as well as the CE terminals and replace. The only things in the way are some mickey mouse interior panels and passenger tray.

This will tell you if there are other compromised circuits. Whether related or unrelated to your issue doesn't matter for now.

When satisfied that nothing is fried, reassemble and resume. If stuff is fried, determine exactly what by tracing wires and refering to diagrams.

Then, I'd resume the alternator replacement program.

85fortheDrive

April 6

I've put Roger's "new" alternator in. It is the exact same Bosch model as the previous one; it is a remanufactured one. I have also removed the CE panel, checked the appearance of the wiring, and eraser-cleaned all of the relay plugs. I'm including a picture of the back of the electric panel; not for the faint of stomach.

Along the way, I discovered the O2 sensor wiring had been disconnected by a PO. Reconnected that, though I'm not sure what that will mean. Car will come down off blocks this AM and I will take it for a spin. More to come.

Thanks, Roger, for sending the new unit. I'm going to hold on to the previous one until I get through some further testing. Spring is trying to get sprung here in Chitown, so it's time to get the shark into the water...

Peace,
Tim

ROG100

Tim,
Thats a real rats nest in the back of your CE panel. If I were you I would remove all the wires and re-attache them in a much neater manner. Must have been done by the PO. Try using different colored wires.
Roger

Alan

85fortheDrive

Well I tried Roger's suggestion and it didn't go well.


Actually, I'm about to get the OB off the blocks and take him out for a spin. Anyone need a gallon a milk?

ROG100

85fortheDrive

April 6 - part two...

Car is all back together now. Took him out for a spin to the Tastee Freeze. Ran like a champion, with no voltage fluctuations whatsover. Still have the DMM connected to the exciter wire circuit. Will take him to work tomorrow for further testing.

Fingers crossed and hand extended to Alan, Chris, Roger, Merlin, and Dave.