OBC will not display on Check Control LEDs

[Pixcutter]

I recently (July) purchased a 1994 540ia. The previous owner had let the battery die. Before I took home the car, he had a brand new battery installed (I watched when it went in). Upon hooking up the battery, the OBC IV displayed PPPP. I cured this by removing the OBC for 24 hours and then re-installing. OBC now works perfectly, but pushing in the turn signal stalk WILL NOT display in the Check Control display. I can't get Prog 1 or anything else.
Now the worst part...In trying to solve the problem, I used my wife's '94 530ia to read out the OBC codes, looking for a toggle that would turn on the Check Control OBC display. Instead, I manged to do the same thing to her car, that is, disconnect the OBC from displaying on the Check Control. Can anyone tell me how to get back the Check Control OBC display? Pushing the BC switch in (Turn signal lever) has absolutely no effect. Can someone get me OUT of the doghouse?

Pixcutter
E34s 540ia, 530ia
So. California

[Paul in NZ]

you have tried pressing and holding the stalk button in for about 5 seconds i think then the prog 1 display appears......

[Kalevera]

The car probably used to have a CNET BMW phone installed in the center console. Pressing the stalk in with the phone installed will answer an incoming call. Often times, they get removed incorrectly and the wiring remains hacked (heck -- it was, to my knowledge, an aftermarket/dealer installed accessory, so it was mis-installed to begin with).

Do a search -- I think a few people around here have fixed it. If not, PM me.

best, whit

[uscharalph]

I recently (July) purchased a 1994 540ia. The previous owner had let the battery die. Before I took home the car, he had a brand new battery installed (I watched when it went in). Upon hooking up the battery, the OBC IV displayed PPPP. I cured this by removing the OBC for 24 hours and then re-installing. OBC now works perfectly, but pushing in the turn signal stalk WILL NOT display in the Check Control display. I can't get Prog 1 or anything else.
Now the worst part...In trying to solve the problem, I used my wife's '94 530ia to read out the OBC codes, looking for a toggle that would turn on the Check Control OBC display. Instead, I manged to do the same thing to her car, that is, disconnect the OBC from displaying on the Check Control. Can anyone tell me how to get back the Check Control OBC display? Pushing the BC switch in (Turn signal lever) has absolutely no effect. Can someone get me OUT of the doghouse?

Pixcutter
E34s 540ia, 530ia
So. California
Did your car's dash cluster's LCD display ever display the OBC readouts?

I'm not clear on what you attempted in your wife's car?

[SRR2]

But that wouldn't explain how he produced the same symptoms in his wife's car where a phone was clearly not involved.

[Kalevera]

But that wouldn't explain how he produced the same symptoms in his wife's car where a phone was clearly not involved.
Steve, of course you're correct on the matter. I can't explain what happened to the wife's car, just that the wires between the OBC and the dash module have been known to be messed up by the removal of the phone.

The body harness is a complex thing. You're the electrical engineer -- I can only speculate what disconnecting and reconnecting the OBC multiple times with the probability of the battery not being disconnected can do to it.

best, whit

[Pixcutter]

My wife's car worked correctly. My new 540 was fried with a bad battery, so I dn't know if it worked. But I'm really in the doghouse (her 530ia is her baby). Thanks.
Harvey

[Paul in NZ]

what exactly did you do to your wifes cars obc????