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Figured I'd post here since this issue pertains to a 2.8l V6, but feel free to let me know if I'm in the wrong.
Long story short, electric fan got stuck and burned the motor out. I replaced the motor, but now the fan doesn't turn on. Tested the motor by wiring it to the battery with a fuse and it works great. I'm not sure what triggers the fan to come on in the first place, I just know that there's a relay involved.
I feel like I should start at the temp sensor (I'm assuming this is what triggers the fan, but please correct me if I'm wrong). Where is this temp sensor/sender?
Once I find it, is the proper test to ground the wire from the sensor to know that the relay is good?
Speaking of, which relay is for the fan? I have 3 relays on the driver's side firewall, not two like I've seen in about every post on this site. It is the 85 Berlinetta model, so I'm not sure if that changes things here.
try asee if the fan comes on when you turn the ac on.
Theres also a fan temp switch in the back of the passenger side cylinder head kinda right by where the valve cover meets the head. its a pita to get to lol
BUT...I know 85 / 96 TPI models had a non- fan switch activated fan..i thnk its controlled by the ECM or something. not sure if the 2.8 was the same.... Try check to see if you got the switch in the head to tell. what you're working with first
Mmmmm those are the older style relay.... they used multiple of the same relay for things like the fan / fuel pump......I disconnected relays til l i found what did what... for example,. i disconnected one, the fuel pump didn't turn on so that was the fuel relay etc...
I'm guessing since its the older style, but I think 3 is the fan relay.
That sensor on the front of the engine is for I believe the temp gauge or light........that's where it is for mine and most others.
The fourth picture..... that is the connector for the distributor....don't unhook that lol
The heads on both pass and driver sides are essentially the same so if you took them off you could put them on either side basically...... so if you had a fan switch itd be on the same location on the back of the passenger head as the sensor on the driver side head in your pic...just on the opposite side and in the back....,,,
Super close!!.....ypur valve cover is right there.....It would be closer to the dipstick, probably under the wire loom in your last pic right on the corner........ if you have the fan switch...if you don;t have one you'd have some kind of threaded plug in the hole I believe.
This is the wiring diagram for the V6 fan circuit. The fan relay is turned on by the ECM or computer. It runs the fan when A&B are jumpered on diagnostic port. This is an easy way to fan if the computer will run the fan. The AC has a switch that also turns on the fan. The engine has to get fairly hot for the ECM to turn on the likely will turn on in hot weather when idling in traffic. If I let me engine idle for 20 minutes or more the fan turns on..
Okay so there's a coolant temp sensor on the ecm. There's also a fan override switch, is that something I can test with? Where's that located?
I looked around on the head and, either I'm blind (absolutely possible) or I don't have something there. I'm going to look again when I have time since it was a pretty quick. It's a MPFI engine if that matters. I'll update with my findings!
Okay so there's a coolant temp sensor on the ecm. There's also a fan override switch, is that something I can test with? Where's that located?
I looked around on the head and, either I'm blind (absolutely possible) or I don't have something there. I'm going to look again when I have time since it was a pretty quick. It's a MPFI engine if that matters. I'll update with my findings!
the switch would be right in the head...its difficultto see so you should look closely...if not you'l lsee a plug...or maybe its caked in crud?
Im curious if that diagram works for the 85 / 86 or if they had the weird TPI fan circuitry as well.
The hard line that goes from the condenser to evaporator along the passenger side frame rail should have an electrical switch on it... if you disconnect it, the fan should turn on all the time when the motor is running. regardless if your ac system is charged or not. that'll also be a good test.
Okay so there's a coolant temp sensor on the ecm. There's also a fan override switch, is that something I can test with? Where's that located?
I looked around on the head and, either I'm blind (absolutely possible) or I don't have something there. I'm going to look again when I have time since it was a pretty quick. It's a MPFI engine if that matters. I'll update with my findings!
the fan override he mentioned is the ECM code test.
if you get like a paperclip and put it in A / B in the diagnostic link, it'll tel lthe ECM its in code mode...the fan wil lturn on as the Service engine soon light flashes codes.
Hey, never did end up figuring this out. Had to take quite a bit of time off from looking into it, but I'm certainly ready to check again. Just working on getting it running again in another thread. Thanks for all the info and apologies for leaving you hanging!
Manifold temp sensor. Plug on passenger side of manifold. I replaced thermostats, relays and fuses and finally discovered it was this little $12.00 part.
I had the same problem with my fan, it would not come on. The ecm would not command it on. I bypassed it with a aftermarket fan controller it works great now.
09-27-2021, 08:07 PM
