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Discussion Starter · #1 · (Edited)
Car: 525td
Year: 1994
Vin number: WBAHA720X0BC35533
Euro / Jap / US New: Euro
Manual
Hi guys I'll keep it short, 1994 525td wouldn't start after I accidently left the charger on for 3 days. Come back, realised what I've done and replace the battery, still wont start. Remove BCM, boom it fires up but now it wont make it past an MOT. Replace "bad" BCM, changes nothing. The windows and central locking had been playing up in the previous few months so thought it was a bad bcm.

Really stuck at the moment, any and all help is appreciated!
 

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D'oh, You Kids!
1984 633CSi, 1985 635CSi, 1985 325e, 1987 325is, 1993 325is, 1995 318is, 1995 M3, 2003 F150
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Welcome to Bimmerfest!

I see you realized your mistake and changed the thread title. I moved your posting to the E34 forum so you can get model-specific help.
 

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Discussion Starter · #3 ·
Welcome to Bimmerfest!

I see you realized your mistake and changed the thread title. I moved your posting to the E34 forum so you can get model-specific help.
Yes, made a complete a** of myself 🤣 sorry.

Thank you for helping
 

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Discussion Starter · #5 ·
when you say the car won't start, do you mean the starter won't crank, or it'll crank but the engine won't catch?
The starter doesn't crank at all, the horn, wipers, electric windows, central locking, sun roof, and the interior lights also dont work.
 

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I would suspect the 80-amp fuse next to the battery -- you can see a thinner red wire from the battery's positive terminal that leads to it. A bad fuse will kill power to all the body accessories you mentioned as well as the DWA antitheft system, which will interrupt power to the starter solenoid.

There is a second main fusible link that delivers power to the starter itself. If that one is bad you won't have any voltage at the jump post on the firewall.
 

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Discussion Starter · #7 ·
I would suspect the 80-amp fuse next to the battery -- you can see a thinner red wire from the battery's positive terminal that leads to it. A bad fuse will kill power to all the body accessories you mentioned as well as the DWA antitheft system, which will interrupt power to the starter solenoid.

There is a second main fusible link that delivers power to the starter itself. If that one is bad you won't have any voltage at the jump post on the firewall.
Thank you, I'll check this and get back to you
 

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Discussion Starter · #8 ·
I would suspect the 80-amp fuse next to the battery -- you can see a thinner red wire from the battery's positive terminal that leads to it. A bad fuse will kill power to all the body accessories you mentioned as well as the DWA antitheft system, which will interrupt power to the starter solenoid.

There is a second main fusible link that delivers power to the starter itself. If that one is bad you won't have any voltage at the jump post on the firewall.
Sorry for not updated thread, car was on the backburner for a bit.
Checked the fuses and they were all good, was doing some digging and phoning around and found out that the BCM is vin locked and that may be why the replacement module wasnt doing anything. Getting it booked into and independent bmw garage to hopefully get it sorted.
Will update if it gets sorted, cheers
 

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Discussion Starter · #9 ·
Update: Fixed, it's taken ages but finally got to the problem. Brace yourself, the two wires that feed power to the box had corroded through... that's all.
Also, spoke to the tech and he said that the vin "lock" doesn't stop it working completely. Idk though take it with a grain of salt.
 

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Is it possible that moisture got under the back seat? Problems with the rear sunroof drains and a leaky rear windshield seal are possible sources. There are many splices under the rear fuse/relay panel, and moisture in them can create problems above and beyond those you've already experienced.

If I were you I'd look for the reason why that power wire got eaten up. Heat from a poor connection or circuit overload can cause corrosion too, but connections often deteriorate because of moisture corrosion. From there the problem snowballs.
 

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Discussion Starter · #11 ·
Is it possible that moisture got under the back seat? Problems with the rear sunroof drains and a leaky rear windshield seal are possible sources. There are many splices under the rear fuse/relay panel, and moisture in them can create problems above and beyond those you've already experienced.

If I were you I'd look for the reason why that power wire got eaten up. Heat from a poor connection or circuit overload can cause corrosion too, but connections often deteriorate because of moisture corrosion. From there the problem snowballs.
I asked the guy at the garage how it looked and he said not the best and to keep and eye on it, thanks for the heads up. Need to get it through an MOT now and some welding must be done but after that ill take a look as to where its coming in.
 
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