LastThirdgen

So I hooked up my radiator fan, used the original fan relay with the black/red, orange, green/white, tan/white wires, went to turn on the car and I get nothing. I'm getting power to the red/black wire so I bench tested the fan to the battery and it does work but for some reason when I connect the black/red wire to the fan the volts disappear. What's up with that?

deadbird

Well... the orange should have the 12V+ on it at all times, as it is power from the battery to the relay. The black/red is 12V+ switched to the fan.
The tan/wht is ign switched 12V+ from the FP FANfuse to the relay coil and the grn/wht is 12V-, switched (grounding the relay coil) by the ECM

The fan won't run until it reaches 'X' temp, depending on how the relay is commanded (coil grounded) to turn on (ecm, a/c or fan temp switch.. varies by year/engine)

LastThirdgen

Yes I understand all of that fully, I have it wired differently until I can get a different temp fan switch, so I have the orange wires directly to the battery, fused of course, tan/white going to the same ignition switched source as the fuel pump, green/white going to the same ground as the fuel pump so it comes on when the fuel pump comes on, and red/black going to the fan. With the car on I get 12volts to the red and black wire, now with the lead still touching the red/black wire showing volts, I touch it to the positive wire on the fan and it instantly goes to zero volts. The fan is grounded to the same ground on the chassis that the battery uses so that's good, the fan works because I bench tested it straight to the battery.. what would cause that?

deadbird

If the relay is pinned out/wired correct, the relay switched wire (blk/red) powering the fan should have 0 volts key on (excluding pump prime). *If* I'm understanding how you have the relay controlled, key on, the fan should start/run for 2 seconds (with the fuel pump for prime)m then run constant after started.... ?

LastThirdgen

I'm not using the original fuel pump relay or ecm so I have the fuel pump wired to where it comes on with the ignition on, no prime function, just on all the time with key on

jcat

because of all the wiring and computer changes you will have to figure it out. draw a diagram on how this is wired and relay controlled.
IMO your fuel pump runs with KEY ON so that is not good ... the reason this is not to occur is if the vehicle gets into an accident and key is on a fuel line breaks gas will continue to flow and you could be barbecued...key on engine off 2 sec prime pump on .. that is how it should be .

the fans do require a computer controlled on time.. speed / engine temp / ac on etc....so this is why ...

sofakingdom

iTrader: (1)

It's impossible for anyone out here to answer an open-ended question like "why doesn't my fan come on" when everything about it has been modified. Especially not when it was modified by somebody else, and even more especially when that person clearly didn't know what they were doing.

It should be illegal to sell dykes to anybody that can't pass some kind of basic electrical test.

The short answer would be, because whoever modified whatever, effed it up. The long answer would be, list every possible thing they could have effed up... which there will ALWAYS be AT LEAST one more thing we didn't think of that they could have botched, and of course that will be the thing they did.

Start by looking at the voltages at the relay, with everything all hooked up. 12V at all times on the org; 12V on the tan/wht with the key on; relay clicks, and 12V appears on the blk/red, when the grn/wht is grounded. Then make sure the temp sw is in the pass side head, and that when the other end of the grn/wht from the relay, that's supposed to plug into the temp sw, is grounded, that the relay clicks. Then of course that when the relay clicks the motor runs.

If the relay clicks but 12V doesn't appear at the blk/red, the relay might be burned up, or the connector might be bad. Won't be hard to spot a bad conn since the most likely thing to be wrong with it is that it will be visibly burnt. Could also be something stooopid like the PO "improved" the wiring by replacing the fusible link with a fuse - LOTS of people seem to think for some reason that that's "better", I can't begin to fathom why - and there's a bad connection at the fuse. In that case of course the 12V will also disappear from the org wire when the motor tries to run.

You can run the fan(s) just off the temp sw, without an ECM connection, just based off of the temp sw, as far as cooling the motor. At that point you can pick the temp you want and buy a sw that operates at that temp. Not sure in your year if the AC system is hooked into the grn/wht so that the fan(s) will run whenever the AC is on, but wouldn't be hard to set up another relay to do that, if not.