This vehicle has the 5.0 litre LB9 engine. Two electrically operated cooling fans are used for engine cooling. The passenger side fan (I think this is the secondary fan) will not shut off while the ignition is on. The operation of this fan is normally that it will switch on when coolant temp is high or when A/C is on. Note that even when engine is cold, i.e started for first time in the morning, the passenger side cooling fan immediately goes on when the ignition is turned on. I have checked wiring harnesses but do not see a problem. I also tapped on relays that switch fan on thinking it may be a stuck relay contact - this did not help.

An additonal problem that has occured at the same time is that the needle on temperature gauge in the instrument cluster will go to full scale and pin itself at full scale as the engine is started. The only way to return to needle to normal is knock the instrument bezel but the next time the engine is started the needle again becomes pinned at full scale.

As I mentioned above, these two problems occurred at the same time. These problems have never occured in the past. Not sure if they are related.

Any ideas? - Thank you in advance.

 

Sounds like the relay is welded. Tapping on it won't help. Try replacing it. Shouldn't be related to guage problem. Separate circuit. Replace the guage.

 

For the needle getting stuck, you need to remove everything infront of it and clearance the side of the guage so that it can't do that anymore. Good chance to fix your fuel guage if it ever does that, too.

If the secondary fan is coming on, the fan switch in the passenger side head is grounding somehow. Wiring could have melted to something, or perhaps if it doesn't appear grounded, someone may have run a second wire inside the insulation and grounded that. It's got to be in the wiring, unless somehow the fan switch is reading really high.

 

I dont know about the fan..but the gauge..mine did it..you have to take the cover off..and then the plastic that is in front of the gauges....tighten all the screws and bolts...then put it back together...the problem is someing came lose and when it reads hot..the little black peice that connects to the neatle..is touching the clear plasitic houseing...you just need to tighten up your screws that hold the gauges in...when you hit the bezel..it pushes it back just long enough for the gauge to fix itself, then in the morn it's back in the norm and gets stuck agian...