W203 Unusual Purge Canister Shutoff Valve Issue:
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2007 S600
W203 Unusual Purge Canister Shutoff Valve Issue:
Greetings,
Here's a bit of a head scratcher, and we are posting this in case someone has encountered this specific problem.
2005 MBZ W203 comes in with CEL and codes for minor leak in EVAP/Purge system. Step 1 was to smoke test, Also removed fuel pump inspection covers, as we have seen small evap leak caused by a cracked plastic closing cover on one or both of the fuel tank units. No leaks detected. While activating the Purge Canister Shut Off in STAR/Xentry, I noticed that it would periodically fail to close fully, so a replacement and harness was ordered. The valve was installed and drive cycle was attempted at private race course. Evap leak fault did not re-appear, but new fault did - purge canister shutoff short circuit to positive.
Valve was removed andno short was found between terminals. The wiring looks goo from inside the luggage compartment to the valve. The jumper harness looks good and has no short, so I elected to replace the valve, since we carry several of them. 50 miles into drive cycle, the fault for short circuit to positive returned.
We will now check the wiring from the valve forward to the ME for a possible short, but we still find it odd that we went from a simple 'minor EVAP leak' to a short circuit to positive.
Thoughts????
Here's a bit of a head scratcher, and we are posting this in case someone has encountered this specific problem.
2005 MBZ W203 comes in with CEL and codes for minor leak in EVAP/Purge system. Step 1 was to smoke test, Also removed fuel pump inspection covers, as we have seen small evap leak caused by a cracked plastic closing cover on one or both of the fuel tank units. No leaks detected. While activating the Purge Canister Shut Off in STAR/Xentry, I noticed that it would periodically fail to close fully, so a replacement and harness was ordered. The valve was installed and drive cycle was attempted at private race course. Evap leak fault did not re-appear, but new fault did - purge canister shutoff short circuit to positive.
Valve was removed andno short was found between terminals. The wiring looks goo from inside the luggage compartment to the valve. The jumper harness looks good and has no short, so I elected to replace the valve, since we carry several of them. 50 miles into drive cycle, the fault for short circuit to positive returned.
We will now check the wiring from the valve forward to the ME for a possible short, but we still find it odd that we went from a simple 'minor EVAP leak' to a short circuit to positive.
Thoughts????
