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randall977
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OBC Questions

Post by randall977 » Tue Jun 11, 2019 10:04 pm

I have a UK 85 M635...

I removed some aftermarket audio wiring from under the dash and found that the red/green wires which supply power to the radio, interior lights etc had all been messed with - I repaired and re-joined them all and everything worked...apart from the OBC display - illuminated but no LCD.

Then, a few days later the car wouldn't start, I fiddled with various wires and then it started and ran fine - not sure what I did. I tapped the OBC relay while the car was running to see if the display would come back - it didn't but the car did stall. Is this just because I'm disturbing the immobiliser relay? Is the loss of display just coincidence?

I really need a spare OBC to test with, a new relay is £80, not too bad but I don't want to replace it for nothing. Thanks for any help!

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TBM
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Re: OBC Questions

Post by TBM » Wed Jun 12, 2019 12:05 am

Randall,

in case you need a new LCD screen: https://www.ebay.com/itm/LCD-Repair-Dis ... Sw1Udc0qvN
'84 M635csi
'86 Lotus esprit Turbo (sold)

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hornhospital
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Re: OBC Questions

Post by hornhospital » Wed Jun 12, 2019 2:43 am

Thank you for that link! I'm going to be the guinea pig. I ordered a repair kit for one of the small OBCs (in my E30). If it works (in other words, if I don't screw it up) I'll get one for the OBC in my 633. Amazingly, the OBC in my far more abused 635 still works!
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann";'87 325is "Odette"; '93 325is "Elvira"; '95 M3 "Ashlyn"; '95 318is "Bebe"

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randall977
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Re: OBC Questions

Post by randall977 » Wed Jun 12, 2019 8:14 pm

Thanks, it might come to that but I don't to go down that route if that's not the problem. It did work...

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randall977
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Re: OBC Questions

Post by randall977 » Sun Jun 16, 2019 8:20 pm

Did some more investigation into the lack of OBC display today. Wiring looks okay, can't find a fault - the backlight functions but no LCD characters at all. I can get a new display as TBM's link, but do displays loose their LCD totally and suddenly like this? Is the OBC display the same on an E30? I can get a spare for an E30 quite easily...

Candycj1
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Re: OBC Questions

Post by Candycj1 » Fri Jun 21, 2019 5:36 pm

Randall - i have a spare working OBC I can lend you for the cost of return postage to rule out a fault with the unit. Usually the screen goes dark (light board replacement) or it bleeds (screen replacement) - yours could be a wiring fault or a problem with the unit. PM me if interested...

Cheers
James

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randall977
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Re: OBC Questions

Post by randall977 » Sat Jul 06, 2019 7:42 am

Thanks to James for lending me his OBC. When I plugged it in it worked fine. It seems like quite a common fault that the display goes blank - I think it's the electronics in this instance. Got a used replacement on it's way, you can actually still buy them new for around £500.

K1W1
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Re: OBC Questions

Post by K1W1 » Mon Jul 08, 2019 12:47 am

I'm hoping I'm as lucky. Am picking up a secondhand one when back in the US later this month, along with replacement screen and LED bulbs in case its either of them. Last thing on the current to-do-list.

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TBM
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Re: OBC Questions

Post by TBM » Mon Jul 08, 2019 2:46 am

Anyone needing a euro OBC I have an extra one.
'84 M635csi
'86 Lotus esprit Turbo (sold)

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