high idle/ cold advance

[redneckaggie]

lately my high idle and cold advance have not been working, I jumpered both of them manually with 12 vdc and they work fine. I have checked the continuity of the sensor in the front drivers side of head an it had no continuity to ground when engine was cold. I was under the impression that this was the on/off for these functions, I did test the voltage coming from the wire into the switch in the front drivers side of head, and it only read 5vdc to ground. where does this power come from? Any ideas on what could be going on?

 

[79jasper]

http://picasaweb.google.com/m/zoom?hl=en&uname=102910104228747408137&aid=5815970899537253105&id=5815971667690689506&viewportWidth=320&viewportHeight=416
So it's hooked in with the FSV.

 

[chris142]

I may be wrong since I'm new to these trucks too but I think that the switch that powers up the fast idle and timing advance has 2 wires. I wonder if you unplugged the wires and put a jumper between them if the fast idle and advance would work, bypassing the switch. This would test the switch.

On my truck there is a single wire sensor near the front and that controls the dash temp guage and should have nothing to do with the fast idle or advance.

 

[79jasper]

Are you talking the one on the drivers side head right above the exhaust manifold?

I may be wrong since I'm new to these trucks too but I think that the switch that powers up the fast idle and timing advance has 2 wires. I wonder if you unplugged the wires and put a jumper between them if the fast idle and advance would work, bypassing the switch. This would test the switch.

On my truck there is a single wire sensor near the front and that controls the dash temp guage and should have nothing to do with the fast idle or advance.

 

[redneckaggie]

the sensor I tested was right below the ac condensor on my 91, I checked the sensors continuity to ground when warm and it was semi conductive at 55 ohms, judging by the drawings posted it seems I should follow the dk blu wire and find where the voltage is dropping to 5v and why. does this seem like im on the right track.

 

[79jasper]

I believe so. On my 88 there's a sensor right behind the coolant neck with two wires on it. It's deep and hard for me to fit my smaller hands into, but it's there. Anyways it should be the one that runs the high idle/cold advance. On my harness in that same area there's what looks to be some sort of relay and it looked to be hooked in with the wire to the high idle/cold advance.

 

[79jasper]

the sensor I tested was right below the ac condensor on my 91, I checked the sensors continuity to ground when warm and it was semi conductive at 55 ohms, judging by the drawings posted it seems I should follow the dk blu wire and find where the voltage is dropping to 5v and why. does this seem like im on the right track.

You said condenser. Did you mean compressor?

 

[redneckaggie]

yes sorry i meant compressor. always get those mixed up and dont know why. i will check for a sensor on the passenger side behind the coolant neck because the sensor that I mentioned in the drivers head seemed to be a single wire set up with no way to operate like a relay like is depicted in the wiring diagrams

 

[79jasper]

I believe the one you checked runs the temp gauge. The one on the far left of the head runs the over temp light.

 

[redneckaggie]

as far as im speaking the front of the head coincides with nose of the truck. Thinking about it now that is probably the overtemp idiot light that I ohmed.

 

[79jasper]

Yes. I use left and right as if you were sitting in the drivers seat.

 

[Fordsandguns]

Seth, the one behind the thermostat housing is the one you are looking for. Just follow the harness from the high idle solenoid and you'll find it. Maybe the plug just got pulled off the switch. That was the problem I had the last time mine quit.

 

[redneckaggie]

awesome appreciate it man

 

[Fordsandguns]

Welcome Seth.

 

[redneckaggie]

yep it does work better when plugged in, just needed to be looking at the correct switch