The power seats of my 1999 C280

- will move after ten minutes of driving;
- will NOT move immediately after engine start; and
- will move after going over a big bump.

Both driver and passenger side behave exactly the same (move or not move) at any given time.

Wiring - Checked. Perfect like new visually.
Fuse Box - Checked front & back. Nothing blown.
Jiggled wires - No Difference.

All moving power seats will fail immediately when the engine is turned off. They won't work for a good ten minutes even the key is turned back on (any position) immediately.

Could this be a RELAY problem? A computer problem? Or somethingelse? A known issue or I am the first victim?

Thanks,
A.

 

sounds like a rear SAM.

 

What is a SAM?

I just replaced the relay module by the fuse box in the trunk. $40 and cures no problem.

 

yes, that one.

what is your VIN?

 

WDBHA29G3XA669846

 

Seems like a loose connection somewhere. Shake down the wiring (again) while an assistant holds the switches, one at a time. If none of the motors works in either seat then it is a component or wire that is common to the entire system.

Check ground connections:
A7 - in trunk rt side, beneath large cover and near relays.
W18 - under drivers seat.
W19 - under pass seat near door sill.

Check relay K24 (convenience relay module) - rt side of trunk.
check module A37 (PSE control module) - rt side of trunk.

Also, it looks like a bad door switch could effect the system?

 

Not a bad door switch because cabin lights responds fine to door status.

Which one is K24 and which one is A37?

I have recently replaced the one located left to the trunk fuse box.

Thanks.
A

 

My 99 c280 just started doing the same thing. The power seats work sometimes and sometimes they don't. Did you ever find out what was wrong and how to fix?
Thanks

 

loose connection most likely, check all conections under the seat and if you can use some electrical contact cleaner fro electronic store to clean the connections.

 

Yes, Indeed our 1998 C280 has had this identical issue for some time. Any update on this?