, Gloucester, MA

February 12, 2013

Why won't dashboard knobs light up?

Auto Scanner
Larry Rubenstein

---- — Q: I have a 2005 Jeep Grand Cherokee Laredo, four-wheel drive, six-cylinder engine, in excellent condition. However, the dashboard control-knob lights are out on the fan, heat control, air direction. All knobs/functions actually work; it’s just that they do not illuminate. I thought it might be a blown fuse, but my Jeep dealership told me it’s not an easy fix. Rather, the entire unit must be replaced at a cost of around $300. Does this sound right to you?

A: This is a common problem for the ’05 Jeep Grand Cherokee, and models a few years earlier than that. The price of $300 from the dealer is pretty accurate. Unfortunately, there is no replacement listed for the illumination bulbs. A less expensive way of fixing the problem would be to check with your local repair shop and see if they can rebuild the HVAC head. I don’t recommend buying a used unit from a used auto parts store; it will only come back to haunt you with similar problems in not too long a period of time.

Q: I have a 2006 Chevy Trailblazer LT, four-wheel drive. It has about 50,000 miles on it and is no longer under warranty. I have recently begun having problems with the gas gauge (and also the digital display of mileage left before gas is needed). Both read empty (0 miles left — low fuel) when the tank has just been filled and for several miles after fill-up. Then it will sporadically jump around between empty and full while I am driving. I have no way of knowing when I actually need gas except to set the trip meter and fill up when I reach 200 miles. So that is what I have been doing. Any idea what is causing this?

A: Most major repair facilities have scanners that link to your car’s computer. With this scanner, they will be able to monitor the signal from your fuel tank and also be able to emulate a signal to your instrument panel. This is how the problem is isolated. Expect to spend one to 11/2 hours for diagnostic costs to be able to nail down the problem. The cost of the repair itself, of course, is dependent on which component has the problem.

Car Care Tip: Lately, there has been quite a bit of controversy concerning tire pressure in the vehicles we drive. A lot of this interest is due to the use of tire pressure monitor systems. Fill the tire to the car engineer specs, or fill the tire to the tire manufacturer specs? This writer is still leaning to the vehicle manufacturer specs.


Larry Rubenstein is a master technician who owns a North Shore service station. His column appears every Saturday. Write to Larry at the Gloucester Daily Times, c/o Auto Scanner, 36 Whittemore St., Gloucester, MA 01930, or send an email to