engine temp sensor problem? anybody... - Diesel Forum

jjqinc · 02-07-2008, 04:12 PM

did some reading and found that after the coolant temp reaches 165f, the glow plug system won't activate when you start up. I've found on my truck that when it's cold, the glow plug system acts normally. Once it gets warmed up, the glow plugs start cycling on their own. I sat there and watched as the needle on my gauge in the truck started going back and forth when the cold idle dropped. Would this mean that there's a bad temp sensor, or bad ground somewhere? Or a bad relay? Anybody have any ideas? Have to get this done--I need the truck thanks

cdnsarguy · 02-07-2008, 05:04 PM

I think there could be a problem with the controller....... but first try disconnecting the cold idle solenoid and timing advance solenoids while running like that, could be a short in some wires.

jjqinc · 02-07-2008, 05:46 PM

thanks for replying . I don't want just start replacing parts without knowing what the cause is. Now that I think of it, I think this started months ago. After the motor reached temperature, the charging(?) gauge in the truck would drop from the center to almost quarter of the way to the left(negative). I didn't pay it no mind. Truck ran fine. I'll let you know how it goes.

cdnsarguy · 02-07-2008, 10:37 PM

Sent you some email info....... check the yellow white wire to the alternator, bad connections will cause major fluctuations ....... that wire is a fusible link......also initiates charging from the alternator. What is the battery voltage engine off........... what is it engine on when fluctuating.

Bill1013 · 02-08-2008, 01:28 AM

You might also see if the radio condenser is hooked up, it may be defective. The condenser is plugged into the short lead off the regulator that's tied in with the yellow/wht. and black/org. If the condenser was a dead short it would blow up, but if it has a low resistance it may upset the regulator charging. Condensers will do strange things. You really don't need it if it's there unless you get a lot of alternator noise in the radio. Also run a 12 ga. wire from the regulator tie down bolt to the alternator frame adjusting bolt. Unplug the engine temp. sensor, that's the one by the thermostat housing, see if that makes a diff, do this after the high idle quits. Just some more suggestions.

cdnsarguy · 02-08-2008, 11:34 PM

Quote:

Also run a 12 ga. wire from the regulator tie down bolt to the alternator frame adjusting bolt.

That would ensure a good regulator ground........