Question: I have a 2006 Honda Odyssey with 90,000 miles. Under hard braking above 50 miles per hour, the car shakes. Below 50 mph, hard braking seems normal with no shaking. Actual stopping performance doesn't seem affected. Your best guess would help me in dealing with the dealer or brake repair shop.
Answer: Front brake rotors that are warped, worn or vary in thickness can cause this type of vibration. A binding or sticking caliper might cause the pads to overheat, creating a vibration while braking at speed. And at 90,000 miles, there may be enough normal wear and tear that it's time for new pads and possibly new rotors.
But don't forget to have the shop check the steering and suspension components for any damage or wear. A bent steering arm, worn ball joint or steering rod end or even a dead shock or strut could cause this type of vibration.
Q: I have a 2008 Buick Lucerne. From day one, the cruise control has not worked properly. It works one day and the next it doesn't. The dealership has replaced a module to no avail. It will work, and I'll stop for lunch for 30 minutes and get back on the highway and it won't work. There must be a switch stuck somewhere. The dealership doesn't know what else to do. Can you help?
A: If by "not worked" you mean that you cannot engage the cruise control, the cruise control switch is certainly a potential culprit. The switch provides a voltage signal input to the BCM (body control module), which then communicates this to the ECM (engine control module). My Alldata automotive database pulled up a relatively simple test measuring resistance through the various circuits of the steering wheel-mounted switch.
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In addition, a scan tool can identify any B-series fault codes in the cruise control circuits.
Q: I own a 3.4-liter 2003 Pontiac Montana with only 56,000 miles. When I recently took it to the dealership to have the engine oil changed, they informed me that my intake manifold gasket was failing and that I should have it replaced. As far as I know they did not do any engine testing. The car does not leak any antifreeze or oil.
After some research, I found out that Pontiac had problems with the intake gasket for this vehicle. What tests are needed to diagnose an intake manifold gasket failure, or can a tech just tell that the gasket is failing by just looking at the engine?
A: In most cases, an intake manifold coolant or oil leak will reveal itself with drips on the garage floor and/or having to add oil or coolant periodically. My Alldata pulled up GM bulletin 03-06-01-010C, dated April 2008, that addresses this issue based on owner's complaints of oil or coolant leaks. Have the dealership show you the physical evidence of leaking: residue, stains or wetness on the engine or transmission.
Internal leakage might lead to oil contaminating the coolant or vice versa. This could be much more damaging to the engine, so make sure there's no evidence of oil in the coolant or antifreeze on the oil dipstick.
Q: Recently, the little box on my instrument panel of my 2004 Ford F-150 went blank. It lights up, but there is no display of odometer, compass or temperature. Any thoughts?
A: A scan tool can check for fault codes from the display itself, and identify any communication problems in the controller area network circuits.
