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thermo fan wont run off. odd consider half the parts are new..

Goon

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Havent driven my car for a year overall..

installed new bigger radiator, thermostat... same old temp sensor and fans.... car has only done 136+k's

couldnt figure out why my cooling fan wouldnt turn on, replaced relay 87 now it doesnt turn off at all.

not sure how long the fail has been going on for in the past since i hadnt driven her in over a year.....

possibly cooked the temp sensor?? is that possibly... maybe the ecu has stored the code?? though ive disconnected the battery and reconnected it.

ive used a 30 amp 87 narva relay to get the big one to turn back on, swapped others for the smaller but nothing...

thinking i may need to create an off and on switch. but surely there must be something ive missed..

she never went past the half way mark on the temp gauge, even before i replaced to relay....
 

Cheap6

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Both fans are on?

Some fault codes will trigger the fans on as a safety measure. Have you checked for fault codes?

The BCM will turn the fans on (for a limited period of time) if the temp. sensor is reading high, even with the ignition off, so it's possible there's a CTS fault or a BCM fault.

Can you check if the BCM or PCM is trying to switch the fans on (vs there being a short somewhere in the circuits)?

One of the fan relays is 5-pin (I don't know which off the top of my head). Has that been replaced with a 4-pin relay?
 

Goon

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The big one is on with the 87 5 pin relay which stays on, on or off i must disconnect to avoid flat battery, the small fan doesnt turn on at all.
I have tried other 87 5 pin relays and no fans occur to turn on at any time. both are 30amp for 5 pin... i think the wiring diagram on each relay maybe why one stays on as its different to the rest, but its the only one making my fans work atm.

I'm about to disconnect the cts and see what happens and test volts etc...

I'm trying to avoid the rig up switch method.
about to check fault codes too.
 

Goon

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mode/set - trouble code = 00000000000000000001000000000000000000
event place 00100100
 

Goon

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discomnnected cts plug, big fan kicks in with the right relay..... thinking cts sensor is faulty?

engine warning light comes on, A/C wont turn on.
 

Goon

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replaced original holden relay, both fans start, engine warning light
 

Goon

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reset ecu replaced cts, nothing still :(
 

Cheap6

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Only the low speed fan relay remains connected to the battery with the ignition off. That is so it can be switched on by the BCM with the ignition off.

I would start by checking if the BCM is switching the fan on. You need a test light or, better, a digital multimeter. For this purpose, Jaycar is currently selling one that is suitable for under $5. If you lift the 5-pin relay out just far enough to access the pins (or you can use jumper wires with male and female spade terminals on either end instead), you can measure the voltage at each of the pins. On the low speed relay both 85 and 86 should have battery voltage (wrt battery negative or body) with the fan off. With the fan on, 85 should still have battery voltage and 86 will be at ground potential (~0.3V above is OK; it's switched to ground through a transistor in the BCM). That will tell you if the BCM is grounding the relay or not.

The high speed fan relay (both fans) is switched by the PCM. It can be tested using a similar method but shouldn't be 'on' with the ignition switched off.

The BCM may be grounding the relay due to it being sent a coolant temp. above the switch on criteria, the criteria for a coolant temp. fault signal being met or there may be a short on the ground wire, including one within the BCM. If you unplug the BCM with the ignition switched off, the fan relay (and fan) should not be running. If it is, there is a short to ground on the wire between the relay and the BCM.
 

Goon

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Thanks mate ill inspect this on my day off tomorrow, it really has me mind boggled.... i've had to manual wire up the thermo fans to switch so i can drive to work...

waiting on my aldl cable too for future use seeing my bluetooth obd2 scan tool wont connect to the ecu..
 
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