Fans wont turn off at all
 

First a little history of the car. Had a issue with the fans not wanting to come on under normal driving conditions which issued coolant seal failure. Rebuilt the motor and now the fans wont turn off at all.

First time around I did test all 4 relays and all of them were great. I dont think they would go bad after the car has been sitting a while?

I should also mention that before I started this rebuild I did forget a ground and tried to crank it, It was the ground on the shock tower. I figured it could be related.

Just looking for help on pinpointing the problem. I know with the fan recall the fans stay on after car was driven, Car wasnt driven yet and I took out the small recall harness by the ECU because I dont have the module.

Any help appreciated.

First, the fan recall is the module and harness by the ECU and there's also a harness between the fan relays and the front harness. The second harness is what "hotwires" the fans so they can run with the key off. Go ahead and remove that.

Next, something is telling the fans to run. I seem to remember that if you don't have the ECU plugged in or one of the grounds plugged in the fans will want to run. Also, if one of the fan control wires is grounded, that could be it, or if you have the AC switch on and an AC fan speed chosen they'll want to run.

Did you remove ALL of the fan recall stuff by the ECU? There's a harness that plugs in between the blue and white plugs on the ECU harness, a ground wire, and the connector going to the recall module itself.

Dale

coolant sensor (back of thermostat housing - green connector) if unplugged will cause the fans to run all the time. Just something else you can rule out to help narrow the search.

My body harness ground wasn't connected and I think it made my fans run all the time while the car was not running. Ecu wasnt getting power either. Not sure if that helps.

Heres the only harness I pulled out, I need to pull out the harness thats at the fan relays.

Attachment 688693

^Yep, that's the fan recall harness for the ECU. I assume you plugged the white and blue ECU connectors back together?

Dale

Yeah I'll double check that I did. Easy to overlook things. So the other harness is in the engine bay between ABS and fan relays?

Ecu is completely hooked up. Blue connector and two white connectors. Ecu ground is also in. Tested relays again and still good. I don't know what the second harness looks like so I didn't rip it out yet. Their in the fender well?

Also half of my UIM grounding strap is missing so I just jumpered it with a piece of wire, I can't imagine that being the cause.

The recall harness to the relays is super easy. Unbolt the relays and unplug each one. You'll see a short harness that goes between it and the main harness. Also, when you remove it, it will clean that wiring up big time, that recall harness is way too big so you end up with a dumb wad of wiring there.

Dale

I see 3 plugs that can go straight to the relays but having trouble locating 4th.

I think it only taps into 3 of the 4 relays.

Dale

Once I pulled out the fan recall harness it seems back to normal. Plugs were corroded and the ones in my relays from the front harness has some corrosion as well. Might have to find replacement plugs for it.

I don't know if this is normal but the fans are coming on whenever key is in ON position now. AC and everything is off.

Taking the fan recall harness out prevents the fans from coming on with the key off. That's the purpose of that harness, to let the fans run with the car off for the 10 minute after you shut down cooling/battery drain :).

Those recall harnesses came packed with some weird ass grease in the connectors, I guess it's a dielectric grease but it's nasty. That's not necessarily corrosion.

There's something else that's telling the fans to come on, something is grounding that relay to kick it on. With the relays unplugged you can probably figure out which one is grounding out then trace that signal to find out what's the input that's grounded when it shouldn't be.

Dale

Yeah I got to figure that one out.

Was running the car earlier but found out that my coolant gauge is not working atm so had to shut it down. And either my aftermarket gauge isnt working or I didnt run the car long enough for the thermostat to open. The sensor is located on thermostat housing, Oh and the thernostat I got from Napa doesnt have a jiggle pin, I dont know if that makes a difference.

Im really scared of overheating again. but at least my fans are stuck on when the key is ON for now.

Read my thread on how to install a water temp gauge. Installing it in the thermostat housing is dumb IMHO, you will get NO reading until the thermostat opens. I use a brass T to install it in the coolant hose to the throttle body, far easier to install there and gives an accurate reading all the time.

The jiggle pin isn't super critical, but on t-stats that don't have one I like to drill a small hole at the top to keep air from getting trapped behind the thermostat.

Dale

Not sure how to go about finding the grounding wire in the harness.

Call me paranoid but should be impossible to overheat engine in 3 mins of idling? Fans were on and ambient temps were 60-70 degrees. Wasn't getting temp response from both gauges so shut her down. Gotta buy a sensor for the stock gauge looks like.

In only 3 minutes you weren't even close to warming up the engine. Again, this is why you don't install the water temp gauge in the thermostat housing, you get NO reading until the thermostat opens.

Go to the hardware store, buy the parts to relocate it into the throttle body water line, and then you can really see what's happening.

The FSM should have troubleshooting steps for the fans.

Dale

The only testing I see in the FSM is relays and fan motors, which were all done.

Also I got to hunt down a very minor coolant leak.

Bump, Im not good at hunting down electrical problems so can someone point me in right direction on figuring this one out? I need to get break-in started.

No idea what can be causing it, Everything outside of the loom is in tact and going where they should be. Unless the problem is in the loom.

Is the EGI fuse inserted in the fuse block by the battery? This will make the fans run too if it is pulled out

I had a similar problem. My fans would keep running long after I shut the car off. You need to take an organized systemic approach to find what's making them turn on, otherwise you will be chasing sensors, AC switches, ECU outputs, and grounds all over the car. Print the page Z40 of the wiring diagram. Next use a miltimeter to figure out which relay's contacts are closing to cause the fans to turn on. Once you have isolated the relay, you have greatly narrowed down what the problem could be. Next, pull the relay with the key on and the fans should stop. Now you will have to figure out what was causing the relay to shut. I would test the coil wires for a potential difference that would cause current to flow through the coil and shut the relay. Then keep checking thinks up stream on the wiring diagram with a multimeter until you find a ground signal or +B that shouldn't be there.

These problems are a PITA, but can be resolved if you use the wiring diagram and start from the symptom (voltage across the fan motor) and trace your way up to the source.

Best of luck and happy hunting.

I applaud your efforts to fix your electrical problems over the past few months. Like you, I have some intermittent problems with the harness including the fans staying on that I tract to that harness pictured above. Moved a wire in that harness and the fans would turn off. You may include the A/C relay in your mix too, because pulling that relay will stop the fans from running, as will grounding the A/C wire (Y/B) that goes into1L.

I'm having my car painted now so the car has been all apart when this intermittent stuff started happening. I also did some harness repairs/fixes before putting the car in for paint. So maybe I wasn't careful with the wires.

One of my intermittent problems is the PFC showing errors 5 volts and highlighted on the sensor check screen of the commander, the car will turn over but won't fire up under that condition. But move the ECU harness slightly, the errors go away, and the car runs.

I should get my car back from the paint shop in February. And I'm busy over the next couple of days with other projects.

I think one thing we need to find out is what are the essential harness wires that power and ground the ECU.

Yeah electrical problems aren't the easiest to track down. I tracked it down to the wiring in the two relays closest to the passenger. Fans stuck in medium and goes to high when AC is turned on so that wiring is working correctly.

Problem fixed. A transistor in the ECU was grounding out.