What's up guys, I've been trying to diagnose the overheating issue due to the cooling fan not kicking on. It used to work and sometimes the relay for it clicked on and off rapidly at times trying to turn on the fan. I ended up replacing the relay... well, that did nothing and the original relay is fine. I tested the wires by jumping them and all of them work. I found this other relay next to the battery on the passenger side with the same color wires as the relay on the fire wall that triggers the fan. It seems to have no effect on anything when I disconnect it, but it has the same color wires... what do the colors specifically control in that case?

Relay found next to battery and cooling fan wires


Cooling fan relay on driver side firewall.

 

http://austinthirdgen.org/mkportal/m...ine_wiring.gif


http://austinthirdgen.org/mkportal/m..._continued.gif

 

I'm educated guessing off above diagrams.


The white relay is cooling fan with the fuseable link replaced with a fuse (blue wire).


The black relay is throttle kicker relay with really faded wires. (due to fading) The pink and black appears as a tan and black.

 

Yeah the white relay is new for the fan and what does the throttle kicker relay do...?

 

Never mind I see what it does

 

It's still a bit strange that the relay was clicking so rapidly. I changed a number of parts on the car already like the coolant temp sensor on the passenger side of the block, fan relay, thermostat. It seems impossible to see why the fan won't kick on anymore. My last option would be installing a manual toggle switch for it. Any suggestions?

 

Sorry missed the cooling fan not working, thought it was a "what is this" question. I'm showing vin H as a single fan.


1. Jump fusable link wire (now BLU fused) to BLK/RED. Fan should turn on. Tests good move to next step, =fan good. Use a heavy gauge wire (fused for safety) small gauge will get hot fast.


2. Check for 12v (battery voltage) on BRN/WHT. Tests good move on =fuse good


3. Jump DK GRN to ground. Fan on = bad coolant fan switch, wire short.


You stated the relay tested good, so the above takes into account a known good relay.

 

Thanks I'll check it out

 

Okay, so I jumped the Blue wire and the fan turned on., the voltage on the brown and white wire is at 1.3 volts obviously not enough and the dr green wire to ground also shows 1.3volts. I am assuming the fuse is somehow blown? I checked them under the dash and I only have the slot for the c/t fan 25 amp fuse, I've seen a few fuse boxes with another fuse for the fan with a 20amp. I guess because i have a single fan and not a dual?

 

The relay with the wires showing would benefit from straightening them out, cleaning them and then use liquid electrical tape on them.

 

Yeah I think they were pulled out once to test them probably... I found the slot for the fuse and what do you know, it blew. But what could have caused it is my next question. Now that a new fuse is in, I have power at blue, brown, and green. I jumped the blue wire, fan turned on, then the brown one (as it was still rotating) and did the same thing right after to the green one. If I grounded the green one nothing happened, so the temp sensor is fine. When I jumped the green one, the fan actually turned on, but the relay was buzzing whenever I jumped it. Another thing is that when the car was on, i pulled the fuse for the fan from the fuse box and it buzzed until i reinstalled the fuse...

 

Ok, lets try this a different way. Remove the relay. With key in run position, using a voltmeter, check each pin on the connector that the relay plugged into and report back the voltages.

 

Okay, I got blue: 12v, Brown: 12v, Green: 0.3v, and black/red 0.3v with the relay disconnected. While I was there again, I swapped the white relay with the original that was in the car. I jumped the black and green and the buzzing was gone and the fan turned on... I disconnected it and reconnected it and tried it again, but it clicked on and off rapidly like before, so I can see that I have to fix the green wire from the connector.

 

I took the green wire fixed the clamp that goes to the connector. I tested both relays and now they are both flickering rapidly when it is trying to turn on the fan at approx 220 degrees. I jumped the green wire again, released it and it stayed on until it got cool, but started flickering again when it got to 220