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No signal to A/C compressor relay

Tiny
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Okay, something is wrong with power off keys out relay clicks and compressor engages, but when I turn the key on relay loses power and compressor disengages. Is there a chance I'm doing the wrong pins on the relay? If I hold is this direction pins 30 and 85 are at the bottom but if I hold the opposite way they are on top?
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Monday, September 2nd, 2019 AT 2:30 PM
Tiny
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You will need an ohmmeter to check for the pin. One end at the compressor and one at the relay. Look for 0.00 ohms.

Roy
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Monday, September 2nd, 2019 AT 2:33 PM
Tiny
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Okay, check did it and still not working. What the voltage I should be getting on the pressure switch?
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Monday, September 2nd, 2019 AT 3:29 PM
Tiny
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One thing I forgot to mention that wiring diagram I found only is for a 2009 Escalade and mine is a 2010 I am guessing they are still the same?
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Monday, September 2nd, 2019 AT 3:33 PM
Tiny
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Yes, what about the relay? Let us do one thing at a time. Your issue is at the relay.

Roy
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Monday, September 2nd, 2019 AT 3:45 PM
Tiny
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Okay, this is what I did and noticed when I jump pin 30, 85 relay clicks like it supposed to, but one I turn the car on the car it disengages. I did noticed pin 86 it is switching depending if car is on or off. When car is off I get 5 volts on pin 86 and it clicks, once I turn it on I get 12 volts and the relay no longer energized. That's the wire that comes from the EMC and it is grounding the relay like you said right?
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Monday, September 2nd, 2019 AT 3:46 PM
Tiny
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Okay, I replaced the relay with the fog lights which is the same and still nothing.
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Monday, September 2nd, 2019 AT 3:48 PM
Tiny
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There should be no voltage to pin 86 with the relay out.

It gets voltage from pin 85 when the fuse block sends the voltage.

I am afraid with your jumping and if you applied 12 volts to 85 to the PCM, you have damaged the PCM.

Roy
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Monday, September 2nd, 2019 AT 3:51 PM
Tiny
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You are still not sure if you installed it incorrectly. That is why you need to do the test I told you.

Roy
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Monday, September 2nd, 2019 AT 3:53 PM
Tiny
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Okay, let me explain my self more clearly I took some pictures. This is with the car off.
When relay is out on lin 86 dos not get any voltage. But as soon as I put the relay then it click and pin 86 get a feedback voltage of 5 volts. First picture is pin 30 and 85 I get 12 volts. I do have a spare ECM switch I just bought.
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Monday, September 2nd, 2019 AT 4:04 PM
Tiny
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Does this look good or the PCM is fried?
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Monday, September 2nd, 2019 AT 4:15 PM
Tiny
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My last answer did not post.

The 5 volts you see is not a feedback, it is a voltage drop between the relay and the PCM.

This sounds like a wiring problem between the relay and the PCM.

Roy
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Monday, September 2nd, 2019 AT 4:22 PM
Tiny
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Okay, what do you recommend? Putting new PCM and risking getting messed up?
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Monday, September 2nd, 2019 AT 4:28 PM
Tiny
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You need to repair the wiring from the relay to the PCM. This is not a PCM issue. At least we are not there yet.

You need a fuse box and wiring repair to start.

Roy
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Monday, September 2nd, 2019 AT 4:30 PM
Tiny
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Should I wait to get the new fuse block before installing new PCM?
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Monday, September 2nd, 2019 AT 4:31 PM
Tiny
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Forget about the PCM for now and do the items needed that we discovered.

Roy
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Monday, September 2nd, 2019 AT 4:33 PM
Tiny
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My question now is, how did wiring got messed up it was working fine three weeks ago?
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Monday, September 2nd, 2019 AT 4:34 PM
Tiny
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Okay, first thing is a new fuse block, right?
Then what would be the second step.
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Monday, September 2nd, 2019 AT 4:39 PM
Tiny
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It could have been working yesterday. There could be corrosion or broken wiring internally.

There is no warning when they fail.

Roy
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Monday, September 2nd, 2019 AT 4:40 PM
Tiny
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Okay, will do I will come back when parts get here.
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Monday, September 2nd, 2019 AT 4:42 PM

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