Q: I have a pristine 2001 Cadillac DeVille DHS with 96,000 miles. I took it to my Cadillac dealer because the "Service Engine Soon" light was on. I was told that code 0741 indicates a sticking torque converter clutch solenoid and would require a transmission rebuild for $4,000. He told me that the transmission won't go into overdrive with the bad solenoid. At 65 miles per hour, the engine runs at 2,000 rpm. Does this indicate it's not going into overdrive? I believe I'm seeing three shifts when accelerating. And if the solenoid does need replacing, does that require an entire transmission rebuild for $4,000?
A: According to my ALLDATA automotive database, the P0741 diagnostic fault code is set when the torque converter clutch (TCC) slips more than its limits for more than 5 seconds when the TCC solenoid is commanded to apply the clutch. There are a number of possible causes for this problem, including low, contaminated or overheating transmission fluid, a sticking TCC solenoid, or a stuck-closed TCC control, regulator or feed valve.
A scan tool can record the "freeze frame" data and failure records, then clear the fault code. During a test drive the scan tool can command the TCC solenoid "on" and monitor the slippage rate for the torque converter clutch. If the slippage is slightly above designated limits, fluid contamination or a stuck valve might be the cause. But if the converter slippage rate is high, the solenoid may be stuck in the "off" position.
All of this points toward a torque converter, solenoid or electronic problem, not necessarily a failing transmission. I'd start with a careful check of fluid level and condition.
And, yes, the higher rpm at road speed indicates no TCC engagement or overdrive.
Q: The tires on my 2007 Yukon Denali keep losing air. The dealership says it is most likely because the rims are rusted. They recommend buying new rims or, for a temporary fix, resealing the rims, which would cost approximately $300. Do you think it's really necessary to buy new rims?
A: Slow loss of air from alloy or steel rims that have had several sets of tires mounted on them is not uncommon. Residue from previous tires along with road dirt and debris can prevent the new tire from seating. Trapped moisture can lead to corrosion. But before spending big bucks for new rims, have the tire from one of the leaking rims dismounted for a careful inspection of the "bead" seating areas on the rim. Unless the corrosion is severe, the rim can be sanded to clean and remove corrosion and sealed to stop air loss. If the rims cannot be saved, it might be possible to find a used set in a salvage yard at a reasonable price.
Q: We have a 2007 Ford Five Hundred with just over 60,000 miles that we bought new. I have noticed that the hood paint is chipping on the very front edge or lip. Dealers told us that unless there is rust or corrosion there was nothing they would do. The hood is made of what looks like galvanized metal so it can't rust. My wife contacted Ford to no avail.
A: First of all, galvanized metal can rust. The galvanization process involves applying a sacrificial coating of zinc to protect the metal for a number of years. Most corrosion warranties from carmakers offer protection for rust that occurs from inside out, meaning the corrosion originates on the base metal and ultimately bubbles the paint.
Typically, rust on the front edge of a hood is caused by abrasion and tiny chips in the paint from road debris allowing moisture under the paint.
The solution is to have the rust properly removed, the metal repaired and the hood repainted. Transparent anti-chip film or a front end "bra" or cover can protect this area from future damage.
