A/C and Fan operation tied to radio?
#1
05-24-2018, 03:43 PM
A/C and Fan operation tied to radio?
Son put a new head unit in the truck - it never had a stock one since we bought it. Previous cheap head unit he used worked OK but he upgraded. No funky problems with cheaper one. Now the new one is causing issues with the A/C Heater control unit AND causes the "4WD Service" light to come on. BTW we have the Infinity stereo with amp in 2001 Quad Cab.
Here's how it works:
If both radio connectors are plugged in the fan won't work which of course keeps the A/C off. And the 4WD service light comes on.
If only the power connector (not the speakers) are plugged into the head unit. Fan and A/C work and no 4WD light.
Sometimes you have to remove the power plug from the radio and put it back in to get things back to normal.
If I remove both connectors but use an alligator clip wire to connect the ground wire to the ground pin on the back of the radio, all is good.
We've checked the grounds, the soldered joints, heat-shrinked them, etc. No joy.
Now, there are a couple of "unused" wires in the original bundle that had a place to go on the original connector and radio. An orange and a white I think.
Why the radio should have to be in the circuit for the blower to work is a mystery to me. Anyone know why? Could I jumper the unused or other wires so the blower works without the radio installed?
Why would the speakers being plugged in cause those problems?
Theoretical fix: get some original radio connectors and splice them back into the harness, get a better head unit that someone makes an adapter harness for and put that in.
Here's how it works:
If both radio connectors are plugged in the fan won't work which of course keeps the A/C off. And the 4WD service light comes on.
If only the power connector (not the speakers) are plugged into the head unit. Fan and A/C work and no 4WD light.
Sometimes you have to remove the power plug from the radio and put it back in to get things back to normal.
If I remove both connectors but use an alligator clip wire to connect the ground wire to the ground pin on the back of the radio, all is good.
We've checked the grounds, the soldered joints, heat-shrinked them, etc. No joy.
Now, there are a couple of "unused" wires in the original bundle that had a place to go on the original connector and radio. An orange and a white I think.
Why the radio should have to be in the circuit for the blower to work is a mystery to me. Anyone know why? Could I jumper the unused or other wires so the blower works without the radio installed?
Why would the speakers being plugged in cause those problems?
Theoretical fix: get some original radio connectors and splice them back into the harness, get a better head unit that someone makes an adapter harness for and put that in.
#2
05-24-2018, 10:08 PM
Legend
I am predicting wiring fault inside the head unit that is causing a ground loop.
Radio connector 1 (Gray) should be:
1. empty
2. driver door negative
3. passenger door negative
4. illumination circuit (white)
5. illumination circuit (orange)
6. Ignition switched power
7. Constant power
Radio Connector 2 (Black) should be:
1. Amplifier activation wire
2. Left Rear positive
3. Right Rear positive
4. Driver Door positive
5. Passenger Door positive
6. Left Rear Negative
7. Right Rear Negative
Radio Connector 3 (white):
PCI bus (not used for aftermarket HU)
Radio connector 1 (Gray) should be:
1. empty
2. driver door negative
3. passenger door negative
4. illumination circuit (white)
5. illumination circuit (orange)
6. Ignition switched power
7. Constant power
Radio Connector 2 (Black) should be:
1. Amplifier activation wire
2. Left Rear positive
3. Right Rear positive
4. Driver Door positive
5. Passenger Door positive
6. Left Rear Negative
7. Right Rear Negative
Radio Connector 3 (white):
PCI bus (not used for aftermarket HU)
