OKay cheers guys, sounds easy enough.
Where is the ECU located?
I know where the fuses and that are.
thanks
Immortality is correct in that you will need to work out why the fan isn't working. The link was intended to answer some of the other questions and provide you with enough info on how the system works to solve your problem yourself. Too hard to cover all the possible variations beyond that.
(The pins to the ECU are labelled by tiny lettering cast into the plastic terminal connectors.)
Extra added bit:
Actually, VNracer, you did ask for detail, so while I can’t cover everything….
Tools: A 50mm length of wire the same thickness as that to the cooling fan, with the ends bared about 10mm. A test light (or multimeter set to measure voltage).
Caveat: use any wiring colours as a guide only. They sometimes vary and I have a VP not a VN.
Ignition on “run“, engine off (red warning lights on dash lit).
Start at the cooling fan relay, under the bonnet.
Pull the cooling fan relay. On one side of the relay will be imprinted a small circuit diagram of how the relay works. It is simply an electrically operated switch, using a low current circuit (85,86) to switch a high current circuit (87,30) which the electrical load , in this case the fan, is on.
On the underside of the relay will be imprinted the numbers corresponding to the terminals. I find it easiest to hold the relay in position above the connector block to ID the wires corresponding to the pins.
On the high current, switched, side, terminal 30 is 12V+ from the cooling fan fuse under the bonnet. The test light when connected from this terminal of the wiring harness (orange/pink) to earth (battery negative or body) should now light.
Terminal 87 (orange/blue) goes to the fan motor. Using the short length of wire to jumper the terminals in the wiring harness corresponding to pins 87 and 30 should operate the fan. If it doesn’t, check there is 12V+ on the orange/blue wire at the connector closest to the fan with the test light to earth (with the jumper wire still in place). If that is good, use the other wire on the connector closest to the fan (black) as an earth instead of the battery negative or body. If the test light lights now, the earth is also good (at least at the low current drawn by the test light). Power in + good earth out = a dead fan.
If the fan and its associated wiring checks out as good:
On the low current, switching, side, 86 is 12V+ in from the ignition relay, via fuse 9 which is under the dash. (If the interior fan works, fuse 9 is OK). There should be 12V+ at this terminal of the wiring harness (pink/white). Check with the test light connected between that terminal and earth (battery negative or body).
85 is the ground/earth/negative side, in this case via pin C1 and the ECM (blue/white). To test this, put the relay back in, ignition off (to avoid the possibility of damaging the ECM while attaching jumper wires). Locate the diagnostic link (ALDL) above the ECM and jumper the black/white and black wires’ terminals together. They are at one extreme end of the connector. A paper clip may work better than the thick gauge wire here and Googling “ALDL AC Delco fault codes” will give a better description of the diagnostic link than I can. Ignition back on and the cooling fan relay (and fan) should audibly click, = “on”. The cooling fan is switched on by the ECM whenever the black/white and black wires are connected and the ignition is on. (This is also the diagnostic mode used flash the ‘check engine’ light and reveal fault codes).
If you do decide to wire around the factory system, save a lot of drama and match the factory system using a relay o
