Heater controls

lightn95

Well-known member
For some reason my heater doesnt work ( fans dont turn on ). I swaped the 60 pin harness with a harness from a MAF truck with seq inj. Is there anything in the 60 pin harness that would control the heater?
I see theres one plug at the end of the harnes that plugs into something around the heater. What is that for?
 
For some reason my heater doesnt work ( fans dont turn on ). I swaped the 60 pin harness with a harness from a MAF truck with seq inj. Is there anything in the 60 pin harness that would control the heater?
I see theres one plug at the end of the harnes that plugs into something around the heater. What is that for?

Don’t think so, my 60 pin is completely disconnected
 
Just because a harness will plug in doesn't mean it's compatible. Did you compare each wire color on the original harness' connectors to each mating pin on the replacement? Which harness are you talking about? The engine bay harness? There's only 1 connector on it dedicated to HVAC.

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What year is your truck, and what year is the donor harness from? The blower motor circuits didn't change much, but there could be differences.

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Steve, i didnt compare the 2 harnesses. My truck is a 95 and i believe the harness was from a 95 also.
In the diagram you posted, what does the C106 plug do? Thats the plug i was refering too
 
...what does the C106 plug do?
It connects wires, like any other connector. I don't understand the question. The function of the wire is shown by the diagram.

If you look in the first picture above, you can see C106 below the letter "y" about midway down. Its actual location is near the blower motor. It's barely visible in this pic, behind a heater hose & a harness loom:

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It connects wires, like any other connector. I don't understand the question. The function of the wire is shown by the diagram.
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Classic... the wire diagrams you posted say C106 is either not used, or not used in a Lightning.
So my question is, what does that wire do in a Lightning? Is it the 12v+ for the motors?
 
Classic... the wire diagrams you posted say C106 is either not used, or not used in a Lightning
What's classic is that you're not looking closely enough - there's another wire in C106 shown in the diagrams. And the note doesn't say C106 isn't used; it refers to that one WIRE not being used in Ls. C101 is made onto the HVAC harness, which is common to all gas trucks. And Ls may not have that wire in the engine bay harness, but they have the other, so they have the connector.

But your question DOES raise an interesting point... In most Ford diagrams, wires that pass through the same connector are generally joined on the diagram by dotted lines (like C101 in most of them). So I may re-draw those to make C106 more-apparent...
...not used in a Lightning.
So my question is, what does that wire do in a Lightning?
It doesn't do anything in a Lightning because it's not used. Your question still doesn't make sense. In other trucks, it tells the EEC if A/C is requested. But Ls are apparently programmed not to need that input.
Is it the 12v+ for the motors?
What motors? There are no motors connected to either wire that passes through C106. One is clearly shown going to the EEC/PCM; the other connects the low cutout switch to the clutch.
 
Hey Brett, looking at the Lightning PCM pinout it does indeed have an A/C cycle press input pin 10 and an A/C panel input pin 43. Ignore my highlighting, no telling what that was for :) Having said that, I'd still start with a multimeter and check voltage at the blower motor and go from there.


PCM pins.JPG
 
That pinout is for all MAP V8s of that year ('94, I'm guessing). It's not specific to Ls, or it wouldn't have a KS on pin 23, PSP on pin 24 (only used on 5.0L), or 4LO on pin 12. And it has pin 56 mislabeled as CKP when it's actually PIP.
 
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Go back to basics. Do you have 12V at the blower motor? If so, can the circuit carry enough current to drive the motor? If yes, you need a blower motor. If not start tracing the power power and ground back to see where things stop. The switch and resistor are both things that can fail and cause this.
 
What's classic is that you're not looking closely enough - there's another wire in C106 shown in the diagrams. And the note doesn't say C106 isn't used; it refers to that one WIRE not being used in Ls. C101 is made onto the HVAC harness, which is common to all gas trucks. And Ls may not have that wire in the engine bay harness, but they have the other, so they have the connector.

But your question DOES raise an interesting point... In most Ford diagrams, wires that pass through the same connector are generally joined on the diagram by dotted lines (like C101 in most of them). So I may re-draw those to make C106 more-apparent...

It doesn't do anything in a Lightning because it's not used. Your question still doesn't make sense. In other trucks, it tells the EEC if A/C is requested. But Ls are apparently programmed not to need that input.

What motors? There are no motors connected to either wire that passes through C106. One is clearly shown going to the EEC/PCM; the other connects the low cutout switch to the clutch.
Wow you must be a blast at parties. Whats Classic is your arogant answers to a simple question. But i guess that to be expected from a socially awkward phuckstick like yourself.
 
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