Hiya folks...

What started out as a beautiful day yesterday turned sour on me when I was stuck in traffic.

Neither my high or low speed fans were coming on. The coolant got so hot it literally filled the overflow reservior and started boiling like a tea kettle. I pulled over and let it cool down.

While it was cooling, I called Boost for suggestions. He mentioned to me that he had cleaned both high and low speed relay fans in the past and to take a look there. I pulled and cleaned the leads on the still good 40 amp fuse, as well as both relays. I -thought- this resolved the problem, but it was apparently just the weather getting cooler. Note that I never actually saw the fans come on.

Now I'm in a situation with scantool data backing me up: The coolant temp is staying spot on at 180-181 when I'm constantly moving over 30 mph, but if I'm moving slowly or stopped for an extended period, the coolant heats up fast (To >245).

FSMs are asking me to do tests with a tech 1, something I don't have available. Any suggestions for diagnosis?

AC on high, see if you have power to the fan leads(?)

Haven't checked that. My multimeter died on me a couple months ago and I've been lazy about replacing it. Guess I know where I'm going tonight.

I swear, Sears needs to rename itself "Adult Toy-r-Us"

When I put the AC to high on that car last year I still had nothing which led me to the fan relays. I pulled them out, tested good on the bench (always nice to have a 12+ power supply handy) and put dielectric on them. Fans came right on and worked great.

Was the pcm commanding them to low at 216ish and high at 225?

FSM is downstairs, but those numbers are close to what its "supposed" to be.

Right..they are close enough for our purposes. W/O a multimeter (you rat...go to work!) the secondary test you can start off with is if your scanner shows the pcm commanding the fans on at the proper temps.

Did it command them on at all?

I can't tell you one way or another if the PCM is commanding them on. I know the car was above both temps and the fans were NOT on. Either the command is not being issued or it is being lost in translation (leads me back to the relays).

I know that the coolant temp sensor is working because the pcm set the check gauges light in the DIC when the temp exceeded 245 yesterday.

By the way, I am at the office. The FSMs stay in the car along with my tools whenever I have a problem.

Scan tool should tell you if the pcm is telling the fans to come on, usually there is something that is labeled similar to "Desired fan setting" and then "actual Fan setting"

Both would be on if things were working properly. In this case you should expect to see the desired to be on and the actual to be off.

As well..another test would be to use a fused jumper and your FSM to jump the hot lead and make the fans come on w/o the relay in place.

I checked for fan activity while the AC was on max and there was none. Bought a new multimeter and I'll test the connections tomorrow. Also, the scantool I have has no parameter for fan settings that I could find so I don't have any way that I'm aware of to check and see whether or not the PCM is even setting the ground to the fans.

Also, I noticed on the scantool that coolant was in closed loop while my temps exceeded what I thought my tstat should be opening at. Does this indicate that I might have problems related to my thermostat or coolant temp sensor?

I'm heading to the yard this morning. Going to find 2 gray relays and replace both. Dialectric greasing them did nothing. I'm open to other suggestions on how to diagnose this problem. Can't sit for more than 10 minutes in traffic right now, which in New York really ain't a good thing.