I'm sorry if this has been answered somehow previously, I did try to search google as much as I could stand and directly here before posting. Information on the Reno/Forenza is quite hard to find.
The shortest way I can frame where I'm at
and stuck right now is the Low Speed / Main Rad fan on a 2008 Reno I'm working on with the owner is never coming on under any conditions. Clearly with the A/C enabled it should be on no? Or at least after the car has driven a while and is hot, but not even then. The fan can
be jumpered to come on so the electric motor isn't gone.
Now long story is
the car has had other issues in the past year too that might tangentially be related, the A/C clutch has not engaged successfully in over a year now, recently the valve cover gasket was leaking and just this week the upper radiator hose tore a paper-cut like invisible crack under where the circular clamp holds it to the output on the front of the engine. I believe the hose that blew recently just finally gave way from heat and pressure of no working fan.
Now today I've been checking relays, fuses, and multimeter checking connectors for the relays and fan.
- There is continuity to both High and Low radiator fan positive + pins at their harness plugs back up into to their relay sockets in the engine bay relay box
- I was able to manually feed the Low Fan (Main fan) power and have it spin just fine.
- Swapping the Fan relays in the relay box with more obviously functional same model relays (the Window rollers) has changed nothing
- There is a third less apparent relay for the fan NOT in the relay box that holds on by a bolt against the frame under the battery and from the wiring diagrams controls both high and low fans on their ground wires after the fan itself. Jumpering the Load pins of this relay and the Low fan relay in the main fuse box totally spins up the fan (only done as a momentary test for crossed / cut / corroded wires! I'm not dense!).
- Multi-meter checking the 'Control' pins of the Relay boxes Low fan (Main fan) relay shows +12v as I would expect with the blower & ac turned on (never mind that the A/C clutch has it's own issue - I just am using that to make the rad fan come on)
- Battery is new - only 3 months old. Should be solid on power unless there is a bad ground or something corroded loosing solid connection? I could use advise on ground points to check if someone has input there
- Never found any fuses or relays that seemed to be bad in either the drivers door fuse box or the engine bay one. I did not pull every one but did continuity test on the little pins at the top of each fuse. Every fuse in both boxes passed.
- Engine light has thrown code P0480 "Cooling Fan 1 Control Circuit".
So this narrows it down to whatever the heck is on the Control side circuit of this relay that's not in the relay box but mounted seperately under the battery area by the name of "Cooling Fan Control Relay" on the wiring diagram (link at bottom) with the model number "96251271". The LOAD half of this relay is fine when jumped across. The Control side is NOT getting +12 when the multi-meter is on it's pins. Which means the relay is not what has failed but whatever acts as the on/off control for it. That's where I'm stuck now, why is this relays control circuit not coming on? How can I further chase this electrical gremlin?
There are connector markings C101, C113, and C108 are on that leg of the wiring but besides recognizing C101 and C108 are connectors leading into the bottom of the engine bay fuse box I don't know how to proceed on the troubleshooting. At this point I kind of cry that true service manual does not exist for this car.
The diagrams here are primarily what has been guiding me through it to this point: Electrical Wiring Diagram 2005 Nubira-Lacetti 9. RADIATOR COOLING FAN CIRCUIT
And most specifically this one