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with the ac off pin # 23 is a ground through the coil, remember all a volt meter measures is the voltage difference between the 2 points, with tyhe compressor off the relay is open = 12v difference. with the compressor commanded on the relay is closed and the volt reading drops to milivolts due to pin 23 being connected to battery volts, the reading reflects the difference between the battery + terminal voltage, and the voltage at pin 23, the lower reading the better, this means that the issue is not a voltage drop in your hot side circuit. i am assuming that when u jumped power to the compressor, that you also jumped the ground as well? if you did this tells you 2 things, 1 with the test you performed last step you have proven that your hot side is ok, and that the coil is functional if you jump power and ground to it. all that leaves is the ground side of you circuit.
next, disconnect the positive battery cable and the ccrm connector and check resistance between pins 15 and 16, if you get more than 5 ohms then your ccrm is open internally on the ground side of the clutch coil. here is the diagram. if that checks out then check between pin 16 and the negative battery terminal, again less than 5 ohms is what you are looking for
Ahhh. Got it. I follow you. I was thinking of the circuit the wrong way. Thanks so much for taking the time to explain all this. I REALLY appreciate it. I can't seem to see the diagram?
And yes, when I connected the coil to the battery I jumpered BOTH the + and - terminals.
I will conduct those two tests later today and report back!
LOL I just read this. I'm guessing you have no idea how electricity or electrical circuits work.
That's some pretty detailed instructions from a "F**ing d**kh**d" who "knows nothing about electricity"!
LMAO, thanks for taking the time to go into this much detail! I'm impressed with your knowledge and the amount of time you spend on the board!
Btw, working on cars professionally here in WI also means that in winter you are working on cars packed with snow and ice in a shop that may
never warm up enough for us mortals! Our techs are not only smart but tough!
That's some pretty detailed instructions from a "F**ing d**kh**d" who "knows nothing about electricity"!
LMAO, thanks for taking the time to go into this much detail! I'm impressed with your knowledge and the amount of time you spend on the board!
Btw, working on cars professionally here in WI also means that in winter you are working on cars packed with snow and ice in a shop that may
never warm up enough for us mortals! Our techs are not only smart but tough!
That's some pretty detailed instructions from a "F**ing d**kh**d" who "knows nothing about electricity"!
LMAO, thanks for taking the time to go into this much detail! I'm impressed with your knowledge and the amount of time you spend on the board!
Btw, working on cars professionally here in WI also means that in winter you are working on cars packed with snow and ice in a shop that may
never warm up enough for us mortals! Our techs are not only smart but tough!
Agreed. Very much appreciative of the meaningful assistance from the " "F**ing d**kh**d" who "knows nothing about electricity"
LOL
And, chromeshadow, I can feel my hands aching now. Sounds miserable.
with the ac off pin # 23 is a ground through the coil, remember all a volt meter measures is the voltage difference between the 2 points, with tyhe compressor off the relay is open = 12v difference. with the compressor commanded on the relay is closed and the volt reading drops to milivolts due to pin 23 being connected to battery volts, the reading reflects the difference between the battery + terminal voltage, and the voltage at pin 23, the lower reading the better, this means that the issue is not a voltage drop in your hot side circuit. i am assuming that when u jumped power to the compressor, that you also jumped the ground as well? if you did this tells you 2 things, 1 with the test you performed last step you have proven that your hot side is ok, and that the coil is functional if you jump power and ground to it. all that leaves is the ground side of you circuit.
next, disconnect the positive battery cable and the ccrm connector and check resistance between pins 15 and 16, if you get more than 5 ohms then your ccrm is open internally on the ground side of the clutch coil. here is the diagram. if that checks out then check between pin 16 and the negative battery terminal, again less than 5 ohms is what you are looking for
let me correct something from the post above before it gets you all turned around, when checking between pin 15 and 16 for resistance, check the ccrm side not the harness side, pin #15 and 16 are connected internally in the ccrm, i believe that is where your issue most likely lies. ity should read less than 5 ohms
Thanks for the clarification. I think in my mind I understood that's where I'd measure between pins 15&16 (i.e. At the CCRM), but I was picturing measuring at the connector, so guess where I would have measured if you hadn't said anything?
Okay, well I'm kinda sad to say, with the DMM self resistance zeroed out, ohms are 0.0at the CCRM between pins 15&16. Furthermore from pin 15 of the harness to the negative post of the battery I have 3.3 ohms. I also measured from pins 23 and 16 of the CCRM connector to their respective terminal points on the A/C clutch coil connector and get 0.0 ohms each.
you still could have a fault remember the ohm function checks the resistance of a circuit with no current flow,there could be 1 strand of that wire left that is connected and it would still read the same as it would if the wire was in good condition, this is where a test light with a filament light bulb comes in handy as i was saying in the first posts i made. with the harness disconnected and the vehicle battery cables connected, using a test light connected to the + battery terminal, probe one end of the circuits you tested with the other end of the circut jumpered to ground,so ..... ccrm disconnected probe pin 15 with the test light= should light the bulb brightly, if not then the circuit has high resistance. then ccrm disconnected pin 23 with test light clutch side jumpered to ground= same thing bulb needs to light brightly, then ccrm still disconnected pin #16 with light and clutch side jumped to ground= buld should light brightly. this will test all the wires on the ground side for high resistance, next with the ccrm disconnected touch to the module pin #23 with the test light and pin #15 with a wire connected to ground= bulb should light brightly. if any fail to light the bulb that is where your problem lies.
Finally had some time to get back to troubleshooting the AC problem on my Mustang today using a test lamp. The lamp I used was a #1156 automotive bulb.
These are the tests I conducted. Hopefully they make sense. "-->" just means "connected to".
Battery + --> test light --> Pin 15 of CCRM harness: test light is bright
Battery + --> test light --> black wire at AC field coil plug, pin 15 jumpered to pin 16 of CCRM harness: test light is bright
Battery + --> test light --> black/yellow wire at AC field coil plug, pin 15 jumpered to pin 23 of CCRM harness: test light is bright
Pin 21 of CCRM harness --> test light --> pin 15 of CCRM harness: test light is bright
Pin 21 of CCRM harness --> pin 16 of CCRM --> pin 23 of CCRM --> test light --> pin 15 of CCRM harness: test light is bright (diode test)
Pin 21 of CCRM harness --> pin 23 of CCRM --> pin 16 of CCRM --> test light --> pin 15 of CCRM harness: test light is dark (diode test)
Pin 21 of CCRM harness --> test light --> ground (CCRM connected and engine running): test light is bright
So all the above equates to A-OK in my estimation. Then I wanted to check out the function of the AC clutch relay; how well current flows when the relay is closed. With the CCRM out of the car, I connected pins 15 & 22 of the CCRM to ground, pins 12 & 21 to +12V, and pin 23 to ground through the test lamp. I can't get the relay to hold. There is a nice responsive positive "click" when I apply power to the relay coil, but it immediately disengages. And I don't even get a flicker through the test lamp. See the YouTube video attached to this post below.
07-27-2015, 12:42 PM
