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I have a 2017 Grand Sport that I am rebuilding. Part of the rebuild includes a new radiator, new A/C condenser and fan module (all purchased from RockAuto) . The fan is not coming on when the engine heats up past 220F, all the way up to 260F. I am not sure if this is related, but another issue is that the LCD display does not work. The instrument gages do work (oil temp, water temp, RPM....)
Does anyone have a check list that I could go through to debug this non-functioning fan? Would it be safe to run the fan directly from the battery to verify that the fan unit is functioning? There are three wires to the fan, 2 large (10 or 12 gauge) and a small wire.
Does anyone have a wiring diagram for the radiator fan?
Very frustrating getting the engine working and have no cooling!
You don't say why you are "rebuilding" it. Sounding like it must have been significantly damaged in some manner, the issue could be about anything, including something as simple as a pinched/broken wire. Have you run a trace on all relevant circuits to see that there is power/continuity, as is appropriate? Is the battery known to be good... for sure? As for checking the fan, if you can do so without mucking with electronics, sure. Be certain of polarity, just in case. Good luck!
One thick wire is +12V always-hot feed from an 80 Amp fuse located between the coolant tank and the underhood fuse/relay box. This fuse is really just a thin metal neck-down strip of the wire lug that goes to the fan. The wire lug bolts to the +12V always-hot battery threaded terminal. There is a black plastic cover over these under-hood battery power distribution terminals.
The other thick wire is ground.
The thin wire is the PWM signal from the PCM that tells the fan controller (part of the fan motor) what speed to run the fan at.
Use a DMM to check for +12V and ground at the fan connector (the car side of the connector). The PWM signal can only be checked with an oscilloscope, or a DMM that has a "Duty-Cycle" measurement feature.
Last edited by ersatz928; Jan 1, 2020 at 05:50 PM.
Thanks for the suggestions.
I was able to verify that the new fan is working by checking it on another C7 Grand Sport.
And I verified that the ground wire on the connector (car side) is good via a connectivity check.
The battery has been on a charger and easily starts the car. It shows 12V at rest, I have not checked the voltage when the car is running.
I am planning on checking the 4 pole fuse box as suggested by ersatz928 tomorrow.
Was the car in a front end collision? If so, maybe the fan was running at the time of collision, and the fan got jammed, which then blew the 80 amp fuse.
Have you checked to make sure the fuse hasn't blown? If the fan was damaged while it was running the fuse may have blown.
If the fuse isn't blown and the fan still isn't working try grounding the ECM control line. As long as the engine is cold the ECM will not be trying to switch in a pulsed ground signal. Also make sure all of your wiring is in good shape. If the fan was damaged the wiring harness may have been damaged as well or maybe the ground circuit going to G102 isn't connected.
What do you mean by fan box? We are working on a 20 c8 that had a front end collision and the front fans aren’t turning on. We have checked and there is voltage have tried new fans but don’t turn on. Harness seems to be good.
QUOTE=nfm;1600732985]Thanks for the suggestions, the fuse block for the fan has shorted - new one ordered![/QUOTE]
Radiator fan not working
