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Odd problem with electrics...
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Author:  doctor924 [ Wed Apr 07, 2010 12:20 pm ]
Post subject:  Odd problem with electrics...

Hi All,

I'm working on my 944 89 project and recently removed a faulty immobiliser from the car.
Prior to the immobiliser removal, none of the electrics worked (no dash, no starter, no fuel pump etc), but the auxiliary circuits did (e.g. external lights, pop up lights also worked fine).

Removing the immobiliser and doing my best to ensure I reconnected all the wires initally cut - I not get the car to turn over, the dash comes to life and most electrical circuits work (bar some bad earths i guess (it was stood for 4 years). But i got no power to the fuel pump. I can direct feed the fuel pump and the car starts fine and idles at 1000rpm steady - it also revs cleanly.

Curiously I also have the 'new' problems:

the fresh air blower motor is 'on' even when the key is off and out of the ignition (it only stops when i turn the key to the '1' position!)(*)
The pop up lights no longer pop up - they come on OK and will retract Ok if i wind them up manually and turn the lights off or turn the ignition off.
The cigratte lighter power is only 'on' when the key is in the same position as the fresh air blower condition above (*)

I'm trying to decipher the Haynes wiring diagrams - but they are tough! I've also got the wiring diagrams from cannell.co.uk - but does it sould like i have reconnected some wires incorrectly - or do i have another fault with the DME/relay??

New to 944's....

Thanks for any comments....

Cheers
Ed

Author:  jameso [ Wed Apr 07, 2010 1:07 pm ]
Post subject:  Re: Odd problem with electrics...

You can jump the DME relay with 3 wires to prove or disprove it. It does sound like you have some errors in your wiring in disconnecting the Immobiliser. When I removed mine I found it easiest to remove the fusebox from above as most of the cut circuits were located there. The other possible culprit is the ignition switch.

Author:  doctor924 [ Wed Apr 07, 2010 1:53 pm ]
Post subject:  Re: Odd problem with electrics...

Thanks for that - will check on the relay problem.
I did remove the fuse box and resplice the wires - but may have missed something so will have to check on that nest of wires again.
Unhelpfully - I also seem to have the porsche alarm system installed too.
With the car starting and idling and revving fine (amazing after 4 years layup) - I am reasonably happy that the sensors and computer are doing what they should be - so do feel I have linked something that shouldn;t be linked (or not!)

Author:  DavidL [ Wed Apr 07, 2010 9:33 pm ]
Post subject:  Re: Odd problem with electrics...

Ed,
The Haynes wiring diagrams have been proved to be incorrect in places. Not sure where exactly but you are better off downloading the workshop manuals from www.cannell.co.uk or from www.promax.co.uk.
Its all free but its a big file so will take a while.

Author:  doctor924 [ Thu Apr 08, 2010 8:46 pm ]
Post subject:  Re: Odd problem with electrics...

Got those porsche wiring diagrams today thanks.
Replaced the ignition switch - which cured my problem with the fan and cigarette lighter being on , when the ignition was off.
Still not getting power to the fuel pump or the headlamp motor yet -but working my way through Clark's garage checklist on fuel pump problems....
Cheers
Ian

Author:  c928jon [ Sat Jun 19, 2010 6:48 pm ]
Post subject:  Re: Odd problem with electrics...

There is a secondary feed to the dme relay that comes from the imobiliser, the dme is two relays in one. This feed allows the dme to switch on the second relay. I think fuel pump is a seperate problem to lights

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