Anyone know how I can I test the engine (radiator) cooling fans and temp sensors?. I scoured the FSM, gone round in circles and nearly disappeared up my own ….!!!. The manual mentions using the Tech 1, which I don’t have.

One fan (drivers side) kicks in at 109c, which the manual says is correct, but I can’t get the 2nd fan to start which I believe should come in above 115c. If I disconnected the first fan at the relay, how hot can I let the engine climb to (for testing the 2nd fan) without damage?. IIRC both fans should run when the A/C is on, unfortunately I can’t test that because I’m still trying to locate parts to repair the A/C.

I’m not sure if this is related, so I’ll put it in the same thread in case:- what should to oil temp run at… mine used to run mid-to-high on the gauge, now it seems to only operate in the very low portion of the gauge (but it does move fractionally)

Try swapping the relays and see if the driver's side fan still runs.
Yea, primary (drivers side) at 109, secondary at 113 (1992).

The secondary relay is the rear one, closer to the firewall.

Also , to see if that relay is working, you can ground the blue/white wire. You may be able to do this without cutting into the wire by clipping a wire to ground and attaching the other end to a probe (like an ice pick). You can get to the relay connector easier if you remove the relays and the bracket.

Grounding the blue/white will turn on the fan if the relay's good.
Note: this will store a code 28 in module 4.1. Just clear that code and ignore it.

The blue/white wire is what is used for installing a manual fan switch (and it always throws that code).

Quote:

The analog gauge even with a good sensor sucks.
I'd suggest you check the digital reading. IF it's off, the sensor may be bad. (See page 8A-201-17 or close to 17 in the 93 FSM). It's just above the oil filter.
My 92 runs at 213F on an 85F day. The higest I've seen is 220.

I use only the digital and never look at the analog gage.

Thanks Bill,

Will follow your suggestions in the morning (01:30 here at the mo) and post findings.

Thanks again for your advice Bill.

I tested this morning by first cleaning all relay connections. Then disconnecting the primary relay and running the motor up to 113c and the secondary fan kicked in just fine. Reconnected the primary relay and that kicked in too (109c). Checked that both fans cut off with +/-5c drop respectfully, so all looks ok. Perhaps I had a dodgy contact.

I think you might also be spot on about the analogue oil temp gauge. Checking the numeric readout showed 110c whilst the water was at 113c so that would probably be closer to the readings you get on your 92. Okay mines a bit higher at 230f, but I was running the engine hot at the time to test the coolant... will test under normal driving next time I'm out, but would you think this 'seems' ok?

That analogue reading is gonna annoy me now, with it hovering around the low end of the scale... I suppose that is a dash cluster job?

Glad it was an "easy" fix. Corroded contacts can sometimes be fixed by simply unplugging and plugging then back in. It's also a good idea to inspect ground wires where they are attached to the frame, etc., they sometimes get rusty.
It's alao possible that the contact in the relay may have been sticking and moving the relay around unstuck it.

Temps sound about right but, your normal test drive will show where you're really at. You should check the "F" readings too. It will take a while for the oil temp to stabilize (longer drive) and the oil temps move up & down slower than the water temp.

Personnally, the only dash gage I glance at is the oil press. I was unhappy with water & oil gages when I first got the car. Now I leave the digital water temp on all the time and really don't look at the dash gages. The only time I even look at the digital oil temp is when it's over 100F outside and I've been driving a long time. I just don't worry about the oil temps at all.
It's up to you how you want to monitor your car though.

The digital vs analog on the oil temp is different from the water temp in that the oil uses only one sensor for the gage and the digital readout. The water temp uses 2 different sensors.

2 things to check, Pull your codes, a code 52 is for low voltage, open sensor/wire signal from the temp sensor to the ECM (you probably won't have this) and you can check the green/white wire from the sensor to the firewall. This sensor is a 3 wire one, the green/white goes to the analog gage, ck for an open or short. The dark green goes to the ECM.