QuestionQUESTION: Yes I am that same person. 1995 Cirrus 2.5 liter 6cyl
ANSWER: Hi Herman,
The only thing I am still unclear about is when you said the fans would come on with one or the other relay "in" did you mean that the fans come 'on' immediately when the engine is cold or only as they should when the engine reaches the temp that would call that fan into play?
In any case, yes you can test the relay activation circuitry from the relay sockets to the power distribution box and to the pcm. (It appears that the power circuits to the fans proper are fine). I will refer to the pin numbers as shown in the manual, not as printed on the relays. Pin 84 and pin 94 of the low and high speed relay sockets should have 12v on them all the time (those are the front pins of the sockets). Check that is indeed the case without either relay inserted and also check that with one relay inserted in either socket (testing at the empty socket).
If that checks out, then focus on the pins at the rear or each socket (86 and 96):
Begin by verifying that you have a connection from 86 to 55 of the pcm, and from 96 to 69 of the pcm.
When the engine is cold and the engine is running you should find that both of those pins show 12v (or possibly are showing 0V but if that is the case that they are "floating", e.g. show infinite resistance to ground; I am not sure which is the case).
Again, measure those pins with both relays out, and with one relay out to see if anything changes and then the other relay out.
The pcm is supposed to ground pin 86 when the engine reaches 104C and ground pin 96 when the engine reaches 110C, which is what closes the respective relays. If that doesn't happen then check the tan/black wire from the coolant temp sensor plug to be sure it is connected to pin 26 of the pcm (and also that the wire isn't shorted to ground) and also test the black/light blue wire from the sensor to pin 43 of the pcm.
Finally measure across the contacts of the coolant temp sensor: when cold it should read 10k-14k ohms, when hot it should read 700 to 1,000 ohms.
Those are the tests necessary to verify the actuation actuation circuits of the fan relays.
Please let me know what you learn.
Roland
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QUESTION: The fans come 'on' immediately when the engine is cold.
(I will refer to the pin numbers as shown in the manual, not as printed on the relays. Pin 84 and pin 94 of the low and
high speed relay sockets should have 12v on them all the time.)--- I think you must mean pins 88 and 98 and yes they do
have power all the time with the key on or off and with relays in either socket.
Pins 84 and 94 have 12v with the ign turned on. Also tested with a relay in either socket.
There is a connection between 86 and 96 of the relay socket and 55 and 69 of the PCM plug respectivley.
[When the engine is cold and the engine is running you should find that both of those pins show 12v (or possibly are
showing 0V but if that is the case that they are "floating", e.g. show infinite resistance to ground; I am not sure which
is the case)]---Both 86 and 96 show no voltage which only makes sense because the relay is not there to close the circuit
but with the ohm meter set at 2K the reading is .534 for both with or without a relay in either socket.
(the tan/black wire from the coolant temp sensor plug to be sure it is connected to pin 26 of the pcm (and also that the
wire isn't shorted to ground) and also test the black/light blue wire from the sensor to pin 43 of the pcm.)---These
check out. The black/light blue wire goes to ground. When I unplug the sensor wire the fans turn off.
The temp sensor is a new one.
ANSWER: Hi Herman,
Correct on the mis-numbering of the pin, my error.
When you say:"Both 86 and 96 show no voltage which only makes sense because the relay is not there to close the circuit but with the ohm meter set at 2K the reading is .534 for both with or without a relay in either socket." I believe this is the reason why the fan comes on when the engine is cold. The relay will close because there is 12v on one end of the coil (pins 84 and 94) and apparently the other end of the coil (pins 86 and 96) are grounded (show 0V) and also are not "floating" but rather show a low resistance to ground (0.534 on the 2k scale, which could either mean 0.5 ohms or 534 ohms, but definitely NOT floating). Thus there is something causing a malfunction of those two pins. I am still confused as to whether both fans come on when the engine is cold, or just one or the other when a single relay is inserted, or does neither fan come on when both relays are in and the engine is cold? So let me know about that.
Did you happen to check when the plug at the pcm was disconnected whether the 86 and 96 pins read infinite or still read 0.543? When the plug is "in" and the engine is cold they should either read 12V or it should read infinite ohms and if not one or the other then you have a short in those wires or a fault in the computer or with the coolant sensor telling the computer the wrong resistance. When the plug is 'in' and the engine is hot, the first 86 should be grounded and then if it gets hotter then 96 should be grounded
That is why the fan(s) come on, but if you say they aren't coming on when both relay are in, either when cold or hot, then again there is something wrong either with the 86/96 wires or the pcm is bad or the sensor is not changing resistance properly. Did you check the resistance across the sensor when cold and when hot?
If you understand the circuit, based upon the above, then I leave it to you to decide which is the case. All the possibilities are listed so you should be able to eliminate those that don't apply and reach a conclusion.
Roland
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QUESTION: Both fans are dual speed.
I tried a new PCM with no results.
As an aside, the garage replaced the distributor under warranty but as I was in the shop I noticed another Cirrus and he said this was the third distributor they were replacing in that one.
As to the rad fans, I tried one more thing, with both relays in and everything connected the way it should be and the motor hot, I unplugged the temp sensor and the fans came on. I replugged the temp connector and the fans went off. If I leave the temp sensor connected and pull one rad fan relay the fans come on. Then if I unplug the temp sensor with only one relay in the fans still stay on. So with one relay in the fans work with or without the temp sensor plugged in. I’m sure the answer is staring me in the face but I’m just not making the connection. I have the wiring diagram as per Haynes manual and it seems the rad fans the A/C and whatever other relay is there all have a common hot feed but these are supposed to be activated by closing the connection to ground.
The key error codes it gave me this time were 22, 33, 35. I’m sure one of those is the air conditioning which I intend to address later. I just don’t have my book here right now. I felt I had checked all of the grounds and tested the wiring but I must have missed something.
AnswerHi Hermann,
The 22 code says the temp sensor voltage was too high or too low...this may have been set when you pulled the plug off the sensor, but why not erase the codes and see if it comes back again? Just disconnect the battery (which will set a code 12) and then check the codes after driving it enough to warm things up fully.
The 33 is about a/c clutch, and the 35 says there is a problem with the low or high speed fan relay activation circuit (which may be due also to your pulling out one relay at a time so like with the 22 erase and recheck). I am not surprised that the fan cames on when you pulled the plug on the temp sensor, it will probably do that when the engine is cold too. The pcm in my '89 also does that as is stated in the manual that when you pull the plug on the temp sensor the fans will come on.
I can't give you any further specific suggestion as to what is going on. But clearly you need to trace through the fan activation circuit to find the reason the coil isn't being grounded on the low speed relay when the temp hits 104 and for the high speed relay when the temp hits 110. I believe I asked you all the relevant questions (though I may not have gotten the answer back for all). At this point I have exhausted the informantion base that I have about the system. I hope you can resolve this.
Roland
