Driving home from work last night the truck developed a random studder that got worse as time went by. Within minutes I was limping into a fast food parking lot with the coolant sensor buried in the hot position. It was ~22°F last night so my first thought was frozen water in the fuel clogging a filter, despite the indicated 15psi fuel pressure (measured after the filter), but when I saw the coolant sensor pegged I knew something else was up.
I popped the hood and felt the coolant hoses and they were just warm, not hot, consistent with the fact that I had just started the truck a few minutes earlier. I even removed the cap (minimal spillage) and felt the fluid, just warm not hot. I checked the fuel bowl/filter and that looked perfectly fine, and when I turned the key on it took a second for the pressure to build back to 15 psi so I know the gauge is working. I also noticed that the coolant sensor started out at the cold position, and then very erratically made its way to the full hot position, all this while the engine was off (behaves identically with the engine running). I started the truck and it idles fine, but pressing the throttle is like stepping on a sponge, the rpms very slowly rise and there's obviously no power there. One time in the past I started the truck with the MAP sensor disconnected and it feels just like that. By now the CEL and the water in fuel light were illuminated as well, but the other gauges appear to be functioning normally (voltage, rpm, oil pressure). I checked the codes (see below) then I unplugged the Edge EZ from both the data port and the map sensor, reconnecting the map sensor to the stock harness. No change. I even tried unplugging the coolant sensor (by the thermostat) and the coolant gauge was unaffected, it still moved erratically from full cold to full hot over about 10 seconds (and then it stays full hot).
Here's the lengthy list of codes, all of which came from the ECU (PCU only had the 1693 code):
- P0112 (M) Intake Air Temp Sensor Voltage Low Intake air (charge) temperature sensor input below the
minimum acceptable voltage.
- P0177 Water In Fuel Excess water found in fuel by water-in-fuel sensor.
- P0178 Fuel Sensor Voltage Too Low, Loss of water-in-fuel circuit or sensor.
- P0217 Decreased Engine Performance Due
To Engine Overheat Condition
Engine overheating. ECM will derate engine performance.
- P0237 (M) Map Sensor Voltage Too Low MAP sensor voltage input below the minimum acceptable voltage.
- P0342 ??? not listed in the 24v code list
- P0562 Charging System Voltage Too Low Supply voltage sensed at ECM too low.
- P0575 ??? not listed in the 24v code list
I had no codes whatsoever before this, and I can't help but notice the repeated "
voltage too low" references, especially P0562. Again the voltage meter appears to be reading correctly, it's around 12v with the engine off and moves up to 14v with the engine running. I looked at the fuses under the hood and on the side of the dash and I didn't see any that were blown, but it was also friggin' cold and I didn't pull each one to inspect it. I just looked closely at the fuse element with my flashlight. I remembered
a post from ToolmanTim that mentioned a connection under the fusebox cover under the hood and that appears to be connected fine (he had different symptoms as well). Again the coolant sensor appears to be the only gauge malfunctioning, and all of the lights on the truck are nice and bright. Even the exhaust brake still works when I'm idling.
I got a ride home but the truck is currently stranded at the same fast food parking lot. I checked all of the ground points that I could see, and I'm at a loss for where to look for this electrical gremlin. Has anyone encountered this before???
02 stranded, appears to have electrical issues
Linear Mode
