Amazon: Bosch dynamo repair

[Ron Kwas]

jp;

You've given only very limited general conditions for anyone trying to help, so you will only very general hints to help...in order for helpers here to give more useful/helpful hints, we should know model, year, modifications/deviations from factory config, complete and specific actions and symptom descriptions, any work which was performed, and why, and results...

Here are comments I can make with info given:

"I tried to start the car and lights AMP and oil light came on OK, starter motor turned a few times but car didn't start." [Fuel? Long time sitting means empty fuelbowls in carbs...cranking for a while might be required to refill them...also some Choke may be needed for initial starting ...What year and model/carb configuration are we talking about here?]
"I tried twice more and now all the electrics are dead, i.e. no AMP or OIL light when key on first setting, no starting. Battery shows 13 V," [If Bat measures 13V but Key fails to turn ON Ign, check all fat wire connections - Bat, St, Chassis)...also check voltage of Bat while helper tries to turn over engine (under Load)...if voltage collapses under load, Bat is flat and needs a recharge, before resuming troubleshooting...]
"....fuses are all ok, I rotated them."[Fuses are not involved in Ign, but as an aside, simply turning them, and taking a chance on if they are making connection or not is bad practice with questionable reliability results...clean to shiny metal and install using ACZP...that will give reliable connections, and confidence, and you can move onto other troubleshooting!]
"Still no AMP or oil lights when key inserted." [Key must be turned to Ign On Position to get AMP and OIL Indicators...]

"Any suggestions what might be wrong? " ...need more and more specific info!]

Good Hunting!

[Pigeon]

Originally Posted by jpws

Fitted dynamo in the car and connected the earth (black cable, right most in my previous picture) and left green and red (DF and D+) disconnected to follow the Haynes manual to polarise the dynamo.
Haynes manual states to disconnect DF and D+, run the engine and then run a cable from battery positive to F.
I tried to start the car and lights AMP and oil light came on OK, starter motor turned a few times but car didn't start. I tried twice more and now all the electrics are dead, i.e. no AMP or OIL light when key on first setting, no starting. Battery shows 13 V, fuses are all ok, I rotated them. Still no AMP or oil lights when key inserted.

As Ron says we're a bit short on information but here's a few thoughts...

This is the wiring diagram out of the green book (click for full size version) - ie. how things "should" be (though be aware that someone may have changed things around a bit at some point in the car's existence, without affecting how it works; the comments below assume that the topology is still as standard):



I don't know what Haynes is on about with flashing the field; you shouldn't be needing to do that anyway and you don't need the engine running to do it, you just make sure the dynamo is earthed and then connect a wire to battery positive and spark the other end against the field terminal.

Here follow some basic tests to give both you and us a better defined starting point to work from:

First thing is to make sure everything is back together as standard, with no temporary alterations, no disconnected wires and no terminals that you loosened and forgot to tighten up again, etc. It may well be that that is enough...

If not, then to begin with, do the headlights work? If they do then power is getting to the ignition switch.

With the ignition on, does the cigarette lighter work? If it does then power is getting through the ignition switch.

With the ignition on and the cigarette lighter known to be working, do the indicators and heater fan work? If they do then the main fuse is OK and the AMP and OIL lights should also be on.

If at this point the AMP and OIL lights are not on, take the wire off the oil pressure switch and ground it on the body (not the engine). If that makes the OIL light come on then power is reaching those two lights. (Don't forget to put the wire back...)

If that's OK, take the thin wire off the D+ terminal on the regulator and ground that wire on the body. That should bring the AMP light on. (Again, don't forget to put it back...)

If all those tests are OK but the dynamo still doesn't charge, there must be a fault in the dynamo, the regulator, or the wiring connecting them. I have a feeling that you won't get that far without having found something, though. Otherwise, report back with your new findings...

[arcturus]

And once again make sure that you have a good clean connection to chassis ground. That would be the first thing that I would check. That connection suffers from corrosion.

[jpws]

Thanks so much for all your helpful suggestions. All good points and I appreciate that I've not provided sufficient information for you to help. (My message was written in frustration for not getting the car working last night; I shall consider more carefully before posting next time in haste).

Using your suggestions give me plenty of things to look at and work on. I will post a full response and more details once I've had time to try your suggestions.

Many thanks