Purchase a Vac/ Pressure pump on E-Bay, Bench tested It functioned. Installed under rear seat and it did not function. Tested brown wire at pump, it was grounded. tested red/white wire, no power. traced red white wire to control module at passenger feet, wire tested ok. QUESTION; is this wire live all time or only when key actuates door locks. My problem is no power in either case. Fuse in C location has power. Any wire schematics for this CM?

Pull up the carpet in the rear passenger footwell. Open the plastic tray with the wire bundles. Locate the wire bundle going forward from the door lock pump. Inside that bundle are two lumps you can see and feel, which are crimped connections for the door lock power and ground.

Typically the crimped power connection gets corroded and goes bad, which causes the system to stop working or become intermittent. Remove the tape, cut out the old crimp and renew it. I stripped the wire insulation back and soldered the wires together.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Yes there should be power at the pump at all times. The rectangular connector is the pump power source, the round 3 pin connector with indent are the feeds from the doors and trunk.

As stated above sounds like a bad connection or broken wire. If it cant be found, just re route a new feed line. Some of these cars have a fair amount of wires in them.

One of my cars, I found a broken wire right where the loom comes into the trunk beside the spare tire, it was hidden underneath the wire cover.

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Just my MB's:
1990 420sel - Winter DD - 410,000km
1990 560sel - absolutely showroom mint - 360,000km!