Truck seems to run fine but SES light comes on constantly
 

Howdy all,
I've had my pickup for about a year and a half now. Last year my mechanic had my truck for about a month to install a PMD relocation kit. This summer it started acting the same as the original visit.

I bought a new PMD module and a 6" cable to mount the PMD away from the engine heat but trying to start it in the morning I noticed the glow plugs would only stay on for about a second. Reconnecting the original PMD would get the glow plugs to stay on and start the truck. Then iId shut it off, reconnect the new PMD, and every thing would be fine until the next morning. My mechanic recommended replacing the glow plug solenoid. Now i can start it up just fine without having to monkey around with cables.

After replacing the solenoid, I get the SES light turning on while I'm driving. It turns on when the engine falls below 1500 RPM and turns off above 2100 RPM. I just pulled the OBD1 codes this morning and got quite a list.

14, 31, 32, 33, 42, 57, 58, 62, and 78.

I can swing a wrench but diagnostics aren't my strong suit. Any help would be appreciated.
Bowenkanobe

Sounds like you disturbed or broke the ground wires connected to the stud at the rear of the passenger side intake manifold when you replaced the glow plug relay.

Your raft of codes all smell ground related,as does the glow relay problem.

Thanks Racer, The ground wires have good connection but I don't like the amount of grease and grime built up on them. I'll be replacing the connectors with new ones and heat shrink.

I found the real culprit for the codes. It turns out I knocked loose the vacuum line for the wastegate solenoid while I was replacing the glow plug relay. I cleared the codes after reconnecting and took it for a good ride. No new codes have shown up and it's running great.

Thanks
Bowenkanobe