95 C280-no cam advance - PeachParts Mercedes-Benz Forum

#1 10-31-2002, 10:49 PM

I've got a 95 C280 and the VCT won't advance. The ground circuit to the ECM never goes to ground. My scanner shows "yes" on the WOT at all throttle positions when the engine is running. With the key on, engine off, WOT is "no" until the throttle is depressed fully. Will that signal prevent the intake cam advancing?

mbdoc · #2 11-01-2002, 08:12 AM

What condition is the engine wiring harness?? Possibly wires are shorted inside of the loom. AT about 2000rpm the solenoid should be engaged by the ECU. WOT doesn't come into play on the cam advance only engine RPM.

#3 11-01-2002, 10:21 AM

I have power to the VCT solenoid, but the ECU doesn't ground the return side. I do have an rpm signal, is that the only input the ecu uses to control the cam timing? On the scanner data, cam control says "no" constantly. If it was a harness problem, wouldn't the control switch to "yes" above 2000rpm but leave the solenoid unenergized?

mbdoc · #4 11-01-2002, 02:32 PM

Have you hooked up a volt meter at the solenoid & reved the engine to see if the command signal comes from the ECU?

#5 11-02-2002, 12:59 AM

I have constant voltage to the cam solenoid, I checked continuity of the ground side from the solenoid to the ECU (it's good). If I jumper the ground side to ground, the cam advances. My manual says that WOT will prevent advance, is that true? And if so, does the WOT signal I'm getting on the scanner cause my trouble?