Hi All,

My cooling fans come on (high speed) whenever the ignition is on. The A/C is off. My brother pulled the relay for the high speed fan and tested it with a battery and voltmeter. The relay was functioning correctly. We left the relay off. Now the low speed fans run all of the time when the ignition is on. We didn't check the relay for the low speed fans. I understand from other posts that the PCM reads a coolant sensor to determine if the fans should come on. Where is this sensor and how do I check it? Also, can the low speed fan relay be causing this problem? Thanks.

Leif W.

I had the same exact problem. Here is a link to it. Hope that is your problem and you can easily find where the break is.


http://www.bonnevilleclub.com/forum/...ht=engine+fans

Hi Azu,

Actually, I saw your post when searching. I didn't see any obvious breaks in my wires, but I'll keep looking. In the mean time, do you know where the coolant sensor is?

Thanks,
Leif W.

Find the thermostat housing and look down on the block. You'll see it there.

If you can have the car scanned. That will help pinpoint the problem.

The relay could be stuck open. Give it a test the same as the high speed. Although they don't typically fail in the position of completing the circuit.

Thanks azu and BillBoost37. I can see the sensor and will check. I'll also check the low speed relay. One question regarding scan codes. My brother does have the correct scanner, but he says it just returns raw data and he doesn't know how to interpret it. Is there a tranlation program or mapping table for the codes (or is he missing something)?


Thanks,
Leif W.

Is it returning at least the trouble code(*)? Is that what he means?

For a complete list of the codes for the 1997 Bonneville, go here . Most of the 1995 codes should be similar if not the same.

I don't know why we don't have a listing for 1994-95 trouble codes, but I'm sure I'll be informed soon enough.

EDIT: OK, I did a bit of research for you. Here'* a link to the codes for a '95:
http://autorepair.about.com/library/...htm?once=true&

Note that this site linked shows a self diagnostic process that I was led to believe does not exist on our cars after '93, so use the code info only until or unless someone here better aquainted with the '95 speaks up.

actrons cp9145 works for that. call ur local auto parts stores to see if they have one in their loaner program, if they have a loaner program that is.