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2nd Gen Ram Tech1994-2001 Rams: This section is for TECHNICAL discussions only, that involve the 1994 through 2001 Rams. For any non-tech discussions, please direct your attention to the "General discussion/NON-tech" sub sections.
On a 1994-2002 Dodge Ram, the EVAP leak detection pump (often attached to the charcoal canister) is located
on the passenger side, mounted behind the rear wheel well liner. Accessing it requires removing the plastic fender liner, secured by clips and screws. It is often found near the frame rail and connected to the charcoal canister.
The FSM just has a vague "if equipped" without specifying which models have a leak detection pump and which don't. What exact model/engine is the truck ? 8th digit of the VIN ?
Also, what is the history of the truck ? Is this a new issue or did it always have it ? What has been done to it ?
Its a 1998 quad cab 4x4. Z is the 8th digit for 5.9. Im assuming it had trouble before because the previous owner changed the canisters underneath. i swapped the purge valve and smoke tested the vacuum system. there are no leaks anywhere all the way to the 4wd harness. i reset it and it will come back on after you shut it off and restart it. holds 19 vacuum at the intake and needle is steady, plenum plate is new from Hughes. the truck kinda smells rich when its running.
P1494 primarily indicates an EVAP Leak Detection Pump (LDP) pressure switch fault. That's an electrical fault, not a vacuum leak. Gotta be a pressure switch somewhere the PCM pays attention to, that isn't working.
There is some anecdotal info on this forum that early 1998 might not have the leak detection pump (it was introduced in the 98 model year). But then the PCM should not throw a circuit error for it either. The "pump" is actually vacuum operated and only has one electrical connection for a sense switch. The whole evap purge/pump contraption in the front passenger side looks like this:
There is some anecdotal info on this forum that early 1998 might not have the leak detection pump (it was introduced in the 98 model year). But then the PCM should not throw a circuit error for it either. The "pump" is actually vacuum operated and only has one electrical connection for a sense switch. The whole evap purge/pump contraption in the front passenger side looks like this:
Wow, nice find. I service three 98s, a 99 and a '00 and don't recall ever seeing that.
