P38A P38 Compressor wont start automatically

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DanClarke said:
So, if you bridge the relays "output side" wiring at the fuse-box the compressor runs; but it won't run even when you see/feel/hear the relay operate? This is illogical.
Click to expand...
wait wait wait there is nothing of that "see/feel/hear the relay operate"
EDIT: it's still the same problem that the relay wont start to work
 
Datatek said:
No, fuse box overheat is a fairly common problem due to failed solder joints and loose connectors. They can be repaired if you are good with a soldering iron.
Click to expand...

I checked the wire connection between the fuse box and the ECU and I have below 0,5 Ohm, so the connection is good.. :/
 
P4wn33 said:
nope which white connectors?
The white connectors are behind the plastic trim at the bottom of the A posts both sides.check for corrosion the best solution is to cut the connectors out, solder and heat shrink the wires.

HAHA yeah the "gefickt" (in english: "fu ck ed") is absolutely brilliant ;D so you mean it help when I spray PCB Cleaner into the fuse box?
Click to expand...
 
Sorry to be so pedantic (or perhaps stupid?)... but is this ground side of the relay missing?
If it was missing then even if the ECU says "RUN" there is no circuit and R20 will never operate and the motor cannot run.


upload_2022-4-4_21-27-22.png
 
DanClarke said:
Sorry to be so pedantic (or perhaps stupid?)... but is this ground side of the relay missing?
If it was missing then even if the ECU says "RUN" there is no circuit and R20 will never operate and the motor cannot run.


View attachment 262518
Click to expand...

hmm.. I can't imagine that, but I will see it when I disassemble the fuse box. But I can only do it on the weekend because I don't have much time this week.
 
P4wn33 said:
nope which white connectors?
Click to expand...

Behind the left hand side kick panel the wires come down by the A-post and there are a load of white connectors. These sonetimes get corroded so people cut them and solder them with that heatshrink stuff around the join.

Hopefully someone can post a picture or the connector from RAVE.
 
Datatek said:
Yes, I saw it after I posted:oops:
Click to expand...
I am not sure we got an answer though.
I thought it would be a good test to prove earth & live continuity out to the compressor and see whether it might be the relay internal contact failed or the relay itself has failed. ;)
I also suggested swapping it for another like-type relay in the fuse-box.
 
DanClarke said:
I am not sure we got an answer though.
I thought it would be a good test to prove earth & live continuity out to the compressor and see whether it might be the relay internal contact failed or the relay itself has failed. ;)
I also suggested swapping it for another like-type relay in the fuse-box.
Click to expand...
I see the OP now says the relay doesn't actually operate, so the problem is between the relay and the ECU or as others have said a bad earth.
 
Datatek said:
I see the OP now says the relay doesn't actually operate, so the problem is between the relay and the ECU or as others have said a bad earth.
Click to expand...
But, if the relay doesn't operate it is either a failed relay (swap it) OR the wiring is bad (fix it) OR when you jumper out the contacts of the relay IF the pump runs it must be the relay has failed. No?
Bridging the relay proves everything else is good if the pump then runs. If it doesn't it is a failed pump or duff wiring but you have proved it is or is not the relay itself.
 
DanClarke said:
But, if the relay doesn't operate it is either a failed relay (swap it) OR the wiring is bad (fix it) OR when you jumper out the contacts of the relay IF the pump runs it must be the relay has failed. No?
Bridging the relay proves everything else is good if the pump then runs. If it doesn't it is a failed pump or duff wiring but you have proved it is or is not the relay itself.
Click to expand...
No signal from the ECU and the relay will not operate, same if the earth path is bad either of which could be wiring or the fuse box.

OP, with the relay removed, put one lead of a voltmeter set to 20 volts in pin #1 of the relay socket and connect the other lead to an earth point, then with diagnostics command the pump to run and see if you get a reading on the meter.
 
DanClarke said:
But, if the relay doesn't operate it is either a failed relay (swap it) OR the wiring is bad (fix it) OR when you jumper out the contacts of the relay IF the pump runs it must be the relay has failed. No?
Bridging the relay proves everything else is good if the pump then runs. If it doesn't it is a failed pump or duff wiring but you have proved it is or is not the relay itself.
Click to expand...

Datatek said:
No signal from the ECU and the relay will not operate, same if the earth path is bad either of which could be wiring or the fuse box.

OP, with the relay removed, put one lead of a voltmeter set to 20 volts in pin #1 of the relay socket and connect the other lead to an earth point, then with diagnostics command the pump to run and see if you get a reading on the meter.
Click to expand...


hehe I'm still allive and I will share the solution but I was not home last week and I didn't really have much time last week.. If the weather is okay, I will check all of that tomorrow :):) but first of all thanks to everyone to help me!
 
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