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Discussion Starter #1
Apologies in advance for this first post but here goes .
Battery connected incorrectly for a matter of seconds then connected correctly .
Tried to start car it just cranks and won`t fire .Also the stereo will not turn on .
Checked fuses in front SAM ,all ok ,rear SAM ,20amp popped so replaced .Made no difference .
A scan with a Snap on ETHOS EDGE produced these codes ,
P 0685
P 0628
P 0087
P 2600
P 2602
P 2643
U 1433
U 0109

All codes cleared except U 0109 ( communication with control unit fuel pump has a malfunction .There is a general failure .Stored.)

The mech mentioned low fuel pressue but did say that theres a signal from CPS .

If it is a fuel pump control module thats gone ,can they be swapped for a used item without the need to programme if the exact same part number is used ?

Any advice will be most appreciated .
Thanks .
 

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1989 W124 260E
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You will need to replace the air bag unit . Inside they have a metal fuse that blows if battery is reversed .Check this on youtube - How to fix no power no start on most Mercedes - Benz Vehicles DIY
 

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Discussion Starter #3
Thanks for the info .
Today has shown progress .
Engine trying to fire with easy start .
Found fuel pump module and ordered a replacement with exact part number .
While under rear seat ,tested for power to fuel pump ,nothing.
So , ran 12v from spare battery to fuel pump and lo and behold the car starts .
No warning lights on dash .
Radio still not working but that can wait .
Hopefully the replacement module will get the car back on the road .
 

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Discussion Starter #4
Tried 2nd hand module .....no difference .
All fuses and relays in front /rear SAMS checked ,all ok .
This is a nightmare , all because of reverse polarity .
 
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