Should the light on the obc always be on?

[karl1171]

I've retro fitted an obc to my 91 525 today. read it was quite common to have no power at pin 17, in fact only one of the required pins had power.

Consequently if took power for the other pins from this one. I got PPPP at first, but when I went back to try again later(ater reading about resetting), it appeared to all be working corredctly as soon as I plugged it in again.

The only problem I can see is the display is permanently illuminated. It dims if I turn the lights on as expected.

I thought perhaps one of the power leads I cut was perhaps swithced at position I, but when I checked with my multimeter found all were still dead.

I'm assuming one of the power leads to the obc needs to be switched(ie power supplied when ignition on), but which one?

[Jay 535i]

I've retro fitted an obc to my 91 525 today. read it was quite common to have no power at pin 17, in fact only one of the required pins had power.

Consequently if took power for the other pins from this one. I got PPPP at first, but when I went back to try again later(ater reading about resetting), it appeared to all be working corredctly as soon as I plugged it in again.

The only problem I can see is the display is permanently illuminated. It dims if I turn the lights on as expected.

I thought perhaps one of the power leads I cut was perhaps swithced at position I, but when I checked with my multimeter found all were still dead.

I'm assuming one of the power leads to the obc needs to be switched(ie power supplied when ignition on), but which one?

I'm not sure I understand your question, but the OBC should not be illuminated when the key is not in the ignition.

[karl1171]

As i suspected: do you know which pin is switched with the ignition?

[Jay 535i]

As i suspected: do you know which pin is switched with the ignition?

No, sorry, but someone will for sure.

Be patient. It's slow here on a Sunday :)

[gale]

As i suspected: do you know which pin is switched with the ignition?

Not sure which pin without reviewing the schematic. Got to the www.bimmerboard.com e32 board and check one of Shogun's recent posts, he has a link to various electrical schematics you can download in .pdf format and the e32 will be similar to an e34 for the OBC.

The OBC lights will be on all the time when the ignition is on. Further, one of the OBC pins will have continuous unswitched power for maintaining its memory settings, but the current draw is trivial. The lights should not be on when you remove the key.

[gale]

Shogun's recent post . . .

http://www.hyrumswebsite.com/BMW_pdfs/

right-click and "save-as" (huge files, hope you have broadband)

[Javier]

Hot at all times: Pin 9 from F20
Hot at all times: Pin 17 from OBC horn Relay (if available).
Hot in Accy, Run, and Start: Pin 8 from F1
Hot in Run, and Start: Pin 6 from F17
Interior illumination source: Pin 22 from dimmer wheel.

Javier