Tracking a Bad Switch
Q:I purchased a new 2WD 2000 Chevy Silverado, and it now has 65,340 miles. One option I chose was rear-shock ride control, activated by a switch on the dash that dramatically stiffens the rear shocks (and the ride) when engaged. The ride-control switch is engaged at least 90 percent of the time because I like the stiffer, more positive feel it offers. It was fine for the first 32,650 miles, until the dash switch stopped working. My local Chevy dealer replaced it under warranty. At 36,050 miles, the new switch stopped working, and the dealer replaced it as well. It consistently goes belly-up about every 3200 miles. I'm now on my ninth replacement switch. I've noticed several times that the gas and temperature gauges begin to flutter slightly and read incorrectly when the switch is engaged and shortly before the switch fails. Also, at times the dash area around the switch is warm to the touch. I have repeatedly given the dealer this information, and he hasn't been able to determine the root cause.
A:GM's Selective Ride Control system adjusts the damping of all four shock absorbers, not just the rear shocks. There's an electronically controlled solenoid in each shock that receives 12 volts from the switch on the dash. You may want to inspect the circuit from the switch to the solenoids, and the solenoids themselves. There may be a circuit shorting out intermittently or an internally shorted solenoid drawing excessive current through the Selective Ride switch. The switch may then burn out prior to popping the appropriate fuse. This may explain the fluttering gauges, warm switch, and repeated switch failure. Another possibility is that the switch was never the problem. Sometimes an electronic device will come back to life during diagnosis or parts replacement because a poor connection in the circuit has been disturbed. It seems fine until you're back on the road and the connection fails once more. Ask the service-department personnel to double-check for any poor connections or shorts and to check the resistance values in each shock-absorber solenoid.
Aligning All Four Wheels?
Q:Is it necessary to do a four-wheel alignment on a 2002 Escalade? More important, is it possible?
A:The Cadillac Escalade, along with other GM trucks on that platform (Yukon, Tahoe, Hummer H2), uses a five-link solid-axle coil-spring rear suspension. This means the wheels are mounted at a fixed position to a common solid axle, and the axle is mounted to the truck at a fixed position in line with the frame. This type of suspension normally won't include provisions for alignment-angle adjustments. An independent rear suspension, where each side of the suspension travels independently from the other, will provide rear camber and toe-in angle adjustments. This allows fine-tuning of the suspension, while keeping each side in relevant position to the other and the rear suspension in line with the front. The answer to your question is that there should be no need for a four-wheel alignment. You don't have to check the rear suspension alignment angle during normal maintenance, and there are no provisions for adjustment. However, if there are significant signs of excessive tire wear in the rear or the vehicle has been damaged during a collision, it would be a good idea to check the rear suspension angles. It may also aid in determining the extent and location of axle, suspension, or frame damage.