Q: Recently my son-in-law replaced the 42RE transmission in his '96 Jeep Cherokee with one purchased at a salvage yard. The transmission works well in all gears except overdrive. It will not go into overdrive when he reaches sufficient speed. Any suggestions on how to get it to go into overdrive?
A: Is the transmission failing to engage overdrive? Or failing to lock up the torque converter clutch? Start with the simple possibilities. Any of the following could cause either of these issues: a faulty thermostat preventing the engine from reaching full operating temperature, a faulty or disconnected coolant temperature sensor or a faulty or disconnected vehicle speed sensor.
Focusing more specifically on this transmission, check for problems with the wiring or connections at the transmission, a faulty overdrive solenoid or a blown fuse or bad overdrive off switch. Internally, a worn overdrive clutch, low overdrive hydraulic pressure or a problem with the lower valve body might be the cause. Start the diagnostics by checking for fault codes with a scan tool.
Q: For the last year when I use the cruise control on my '99 Ford Explorer at speeds 65 miles per hour and higher, I notice that the cruise control engages and disengages every half to one second. The vehicle repeatedly surges forward, then backs off abruptly. The accelerator pedal is constantly moving back and forth as if I am depressing it and then releasing it.
Recently I was on the interstate and set the cruise control at about 72 mph. It immediately started the "jerking" cycle. After about 15 minutes the ABS light suddenly came on. I touched the brakes to make sure the brakes were working OK, and the cruise control disengaged. I then hit the cruise control resume button, and the cruise control no longer had the jerking motion. It was as smooth as the day I bought the vehicle.
Any ideas on the problem? Is there a correlation between the cruise control behavior and the ABS light?
A: My Alldata database identified a series of service bulletins focusing on the cruise control system used in this vehicle. Both the cruise control cable and the deactivation switch have been subject to specific recalls. Check with your dealer to see if your vehicle was included in these recalls.
The fact that the throttle position is changing indicates the cruise is not disengaging; rather it's hunting back and forth trying to establish the preset speed. A scan tool can search for diagnostic fault codes from the ABS and cruise control. And yes, a problem with the ABS control module could cause the type of cruise control speed fluctuations you've described.
Q: I brought my 2006 Toyota Camry LE sedan in for its scheduled oil change. It has 37,700 miles. I was shocked when the service department at the Toyota dealership where I purchased the car told me I have two serious problems - water just starting to seep out of the engine block, so the water pump must be replaced for $450, and oil just starting to seep out of the oil pan, a $315 repair. They did not show me the problems on the car in the garage. They also offered to have the work done immediately.
A: Since neither of these problems is immediately serious, you did the right thing by not having the work done at that time. Absolutely have another Toyota dealer or a trusted independent check to confirm whether or not these leaks exist. If they do, you still have options. Adding a stop-leak product to the cooling system may well reduce any minor coolant leaks significantly. Checking the oil pan mounting bolts may do the same for the oil seepage.
As long as the engine doesn't run low on coolant or oil, no damage will occur. By monitoring the situation closely you'll know whether the leaks are significant and need immediate attention or minor ones that can be postponed.
Paul Brand, author of "How to Repair Your Car," is an automotive troubleshooter, driving instructor and former race-car driver. Readers may write to him at: Star Tribune, 425 Portland Ave. S., Minneapolis, Minn. 55488 or via email at firstname.lastname@example.org. Please explain the problem in detail and include a daytime phone number. Because of the volume of mail, we cannot provide personal replies.