Replace ignition switch

[T.Hanson]

Can we tell I'm remodeling my new jalopy ? More posts than a picket fence.

The battery is new, passed load tests, but goes dead sometimes. No sparks scraping the post(s) with ignition off after wiring clean up. Four healthy starts after four, six hours, twice after overnight.

Dead again. Wiggling the key can get the instruments to dance on/off and the tumbler feels mushy compared to other 528's. Suspect ignition switch isn't always going off completely.

Can I swap in the one from 633/635 or are they destroyed in removal ?

Am I in for a hassle treat or is it not too difficult ?

Provided that's the problem.

Thank you,

[Falkenberg]

Interesting. I am experiencing some issues as well lately.
After I changed the engine, starter did not engage except once. But when I would turn the key, I would see the lights in the dash dim a bit, so obviously some current was going somewhere. I figured, since I have no spare ignition, that it was worth a try to add a relay to the starter circuit.
Hoping that the ignition switch would have enough power left to command the relay.
Indeed, it does. But now sometimes the starter just goes cranking even if I don't have the key in the ignition. It seems that in certain cases, a current is leaking through the starter circuit. Big enough to make my relay switch.
I was planning to open up the ignition switch and try to fix it. But the list of to-do is quite long.

[Robert Bondi]

Ignition switch is a possible culprit. The symptoms also suggest checking your relief relay. Its job is to divert basically all available current from the battery toward the starter while turning the engine over.

[T.Hanson]

Where might be the relief relay on an '81 633 ?

There is a relay with 4 large red and red w/ green stripe wires plugged into it. It has a tab on the rear top for a sheet metal screw to mount to the inside fender near the battery,...someplace.

The positive battery cable has a tab on it with two fat red wires bolted to it, one going to that relay (now just laying between the battery and the black plastic headlight body cover.)

Something is draining the battery. My plan is to attach a test light and have somebody wiggle the key to see if it's not always going totally off.

Thank you for your help.

[Robert Bondi]

Someone with an E24 will have to chime in on the location. On the E12 (77 530i), it's one of the 4-prong cube relays inside the fuse box.

Robert

Where might be the relief relay on an '81 633 ?

There is a relay with 4 large red and red w/ green stripe wires plugged into it. It has a tab on the rear top for a sheet metal screw to mount to the inside fender near the battery,...someplace.

The positive battery cable has a tab on it with two fat red wires bolted to it, one going to that relay (now just laying between the battery and the black plastic headlight body cover.)

Something is draining the battery. My plan is to attach a test light and have somebody wiggle the key to see if it's not always going totally off.

Thank you for your help.

[T.Hanson]

Thank you. I'll use that as a place to start looking.