97 F-355 RH Fan not running - Not relay, fuse, or sensor.

So this will be an in-depth look at the F355 electrical system with regard to the secondary RH fan.

Once again, seems like I can't get the easy problem/solution, so into the bowels of the F355 shall I tread once again. I can't wait to get to CA where I can install a proper lift and really tear the car all the way down and fix it once, properly.

Just a little background... I am a former Avionics technician, which means I am dangerous with an Ohm meter and might be able to use an O-scope... Not afraid to break it, just like I wasn't afraid to break 50-90 million dollar aircraft.

Ok, so here is the story, generally stock Ferrari with a re-flashed ECU from Fabspeed, which appears to otherwise operate normally and I don't remember the problem occurring until I arrived on Guam. Car generally runs cool as soon as it starts moving but temps begin to creep up dangerously high, if I sit for too long (not gonna cut it in LA traffic).

Brief inspection shows that the LH fan operates normally and kicks on at the appointed time and place per the manual. The right hand fan, does not kick on even at 220-240 degrees (water) 210 (oil).

Troubleshooting so far has included the following:

1. Inspecting fuses - No Faults.
2. Swapping Relays - No change in either fan (LH works, RH does not)
3. Resetting ECU - Disconnect ECU to look for bent or damaged pin - No faults
4. Jumper the RH fan relay- RH Fan will fire-up immediately and allow the system to keep cool idling indefinitely as intended.
5. Disconnect the Oil Temp Sensor - Results in temp gauge minimum value.
6. Grounding the Oil Temp Sensor Wire - Results in temp gauge maximum value.

For those who want to know:

Fuses and Relays are located in passenger foot well. (It's all well labeled in there)

Fan Relays:
Pins 30-87 are the ones to jumper to test the fan wiring.
Pins 86 and 85 are voltage/ground for the relay magnet. Pin 62 on the 5.2 Motronic (RED/BLUE wire) should be pulling to ground.

Oil Temp Sensor is directly underneath the Oil Reservoir

So, I believe, that should I find voltage on Pin 86 (and I believe I will), that the problem is either the ECU or the wiring between Pin 85 and the ECU pin 62.

Whew... Is that it?

Mark

 

Ok, well pin 86 had voltage (7v, I was expecting 5v), and pin 85 had more voltage (14v). So the ECU is not pulling that wire to ground but it is certainly putting voltage on the pin, so I know that the wiring from there to the ECU is good... Making this a black box problem. Argh.

Time to call the people who reprogrammed the box, most likely something is amiss in the flash, as the rest of the ECU works perfectly fine.

Mark

 

Every time I called them, they broke something else....

LOL, it's definitely in the ECU, I might wire a bypass for now to get the relay to engage when the other fan kicks in. Seems like the easy way to work around it until I can get a definitive answer.