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I was planning on getting a hold of a ATF guage and dropping my transfer case early next week. Now my elec cooling fan has decided to quit working, or I should say, not quit working. The list of stuff to fix seems to keep growing.
The damn thing just wont shut off. When I was on my way home tonight I stopped at the store for about 20 min. When I parked it was on, and when I got out of the store it was still on... although slowly
It ran for about 40 minutes when I got home. Where I am at in PA it is in the 20's right now, and the temp gauge is reading about 205 when fully warmed up.
My first thought is the elec thermostat is done. Anything else I should be looking for while I am digging around down there??
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sounds like the electric thermostat (as u said) is done. its the only thing controlling the fan (AFAIK). tis probably shorted out?
im sure your radiator is filled up with antifreeze and has no leaks?
sorry cant be of more help.
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The electric cooling fan is switched on by a relay in the Power Distribution Center (PDC). Try pulling the relay out and the fan should stop. Sometimes the contacts in one of these relays will weld together and stick. Try swapping with the AC relay and see if that doesn't make the fan run when it should. Don't plug the bad relay into any other slot. The coil of the Coolant Fan Relay is grounded by the PCM (Power-train Control Module) when the coolant temp sensor indicated the engine coolant temp is above a certain point and/ or when the PCM calls for AC clutch engagement. The coil power is IGN switched but the power to the relay contacts is through battery fuse 15 in the PDC 20A. Given your description of the symptoms, it sounds to me like the relay has stuck contacts. A new relay should fix it easily. It is a common Bosch style relay used in many other vehicles too.
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I will have to check the relay and see if that helps it.
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Not sure what year you have, but most of the XJs have a relay that actually switches the fan on. It is probably stuck. An easy fix if that is what it is.
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My XJ is a 98
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Replace the relay.
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I've seen electric cooling fans quit working on lots of vehicles, and rather than track down the relay or fault, it is much easier to just run the fan directly to a toggle switch powered off the fuse box. If you don't want to manually switch the fan on and off you can just run power to the fan from a "Hot in Run" circuit to where if your key is on, then the fan is spinning. It's easy to find out which circuit is which with a test light or multimeter at your fuse block beneath the dash. Some may prefer to keep the original relay and circuit, but mines an '88 with no shortage of wiring and electrical issues.
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I pulled the relay and the fan shut off. I'll just get a new one and see if that works. If not I might think about a switch, but the relay seems easier right now
Before I posted to the group I was on a few websites investigating the ghost fan that didnt shut off. There are a bunch of blogs out there with guys who do all sorts of stuff to their XJ. One of the common cooling upgrades is swapping the stock thermostat for a 180 degree one. (now I am talking about radiator, not electric)
I dont have any overheating issues, my 98 XJ runs 205-210 all the time. One of the general agreements on those blogs is the XJ runs hot.
What do you guys think??
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Yes this is very true until the engine control goes into closed loop. In closed loop the oxygen sensor becomes the primary feed back sensor for mixture control. The coolant temperature is still monitored and becomes a secondary input for mixture control. When the throttle is suddenly opened the enrichment curve is directly calculated by the coolant sensor input. Also above 70% throttle the oxygen sensor feed back is ignored and the coolant temperature sensor again becomes a primary sensor. The MAP and intake air temperature sensor are always primary sensors for mixture control.
Running the engine cooler will make the mixture richer in several operating modes.
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The ECM adjusts fuel mixture based on engine temp. When the engine is less than 190 degrees it makes the air fuel mixture richer. If you put in a colder tstat it will affect your fuel milage. And 205 - 210 is normal for a 4.0 XJ
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I just swapped the relay for a new one and it is back to working like normal. easy $10 fix, I just left the thermostat alone. I already get crappy mileage compared to my corolla and have no intention of making it any worse.
The thing runs good despite me best efforts to break it
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There is one good reason for this, as well as wiring parallel circuits so the AC will function with the aux fan also. At low speeds, such as stop and go traffic and off road applications, turning on the fan before the engine reaches 217* is sometimes a good idea. Personally, I run two high output electric fans on a 200* automatic switch in parallel with the AC circuit. My temps to not exceed 195*. It isn't for everybody, but for some it might work better.
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