Letters: PCM could be cause of Rendezvous woes

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2004 Buick Rendezvous

Updated: November 1, 2011 1:32PM

Q: My wife’s 2004 Buick Rendezvous has a couple of problems. First, the fuel gauge is acting up. As the vehicle is driven and the fuel gauge approaches the halfway point, the gauge will suddenly drop to empty, even though the tank is not empty.

It has been taken back to the local Buick dealer four times and they can’t find the problem. There are no codes, either. The last time it was in, the service advisor stated that he thought the sensor and the float were not properly aligned and that one of the baffles in the tank was causing the sensor to read empty. When they took everything apart, it checked out OK and they put it all back together. The problem is still there.

The other problem regards the cruise control. It will work for about five or six times and then it will stop working. We can get it to work again by turning the engine off and back on again. I believe that there is a computer problem, but I do not want to pay $875 for a new engine control module and have the problems reoccur. Do you have any advice? – Reinaldo, e-mail

A: It’s possible that the two problems could be associated with a problematic powertrain control module (PCM). But it’s also possible that the two problems are unrelated.

Regarding the fuel gauge issue, the fuel level sensor in the fuel tank could still be the problem. A technician should be able to substitute the value of the resistance for a tank that’s ¼ full to see if the PCM and instrument cluster are OK.

As for the cruise control, there’s a separate cruise control module that could be the problem. Or something could be wrong with the cruise control switch.

Q: I own a 1994 Buick LeSabre with 190,000 miles. The problem is that there’s a burning smell coming from under the hood. It smells like burning oil, but nobody has been able to find the source. One mechanic told me it was the valve covers and after replacing them the smell was still there. I even had the engine steam cleaned and the smell came back. What do you think it could be? – Joe, Bridgeview

A: It could be a leaking oil pressure sending unit. The sending unit is located on the backside of your LeSabre’s engine not too far from the serpentine drive belt. Oil could be getting stirred around by the turbulent air of the drive belt and then end up being deposited on the exhaust manifold. A technician should have checked the sending unit. Over time, they’re known to leak.

To help pinpoint the source of the oil leak, a technician can pour in a small amount of ultraviolet dye into the oil and then use a black light to help identify where the leak is originating. The technician may need to use a long, skinny inspection light with a mirror attachment to look in tight spots.

You may want to contact repair shops in your area to see if they have such equipment. This type of equipment is affordable and most shops should be equipped. I would not recommend continued driving with the burning smell because of the potential of the burning oil starting a fire.

Questions for Ira Siegel? Call the Auto Advisor Hotline at (708) 633-6839 or e-mail autoadvisor.irasiegel@gmail.com. Siegel is an automotive instructor and an automotive service excellence-certified master auto technician.