Auto Doc: Isuzu transmission troubles

Isuzu Rodeo.

Isuzu Rodeo. Photo Credit: WikiMedia Commons

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Dear Doctor: I have a 2002 Isuzu Rodeo V-6 with an automatic transmission and 152,000 miles on it. Recently I noticed while on the highway as the transmission pushes toward fourth gear the rpm increases and the transmission will not shift, unless I accelerate to 80 mph (3,800 rpm), whereby it shifts and the "check transmission" light comes on. After that the rpm drops and it runs normally at highway speeds, it does however, shift harder at the lower speeds while the check light is on. What do you think? -- Gary

Dear Gary: Before any decision on repairs can be made the technician will need to check the fault codes that are in the computer. The transmission is electronically controlled. It may be best to take the vehicle to a transmission shop. Running the engine at a high rpm in order to get it to upshift with 152,000 miles on the odometer could cause internal damage to the engine. Whenever we get a vehicle like this we check both Identifix and Alldata systems for a history of other owner problems as well. -- Doctor

Dear Doctor: I have a 2001 Ford Explorer showing a message on the code reader that it was unable to establish connection after I had a "check engine" light on dash. The vehicle runs fine, but I brought it to the dealer hoping he could reflash the ECM. The dealer replaced the ECM and programmed it twice because the VIN would not read on the code reader. He tells me there is nothing else they can do. I cannot pass inspection without a properly displayed VIN readable through the OBDII port. What am I to do? -- Rich

Dear Rich: The most common fault with no-communication is no power to the ALDL connector under the dash, and/or a blown cigarette lighter fuse. The first step is to check all of the fuses. We use a break-out box that plugs into the ALDL connector for checking voltage. There are companies that will repair the computer in your vehicle, or replace it, with your original VIN number in the replacement computer if needed. We use a company in Pennsylvania for ECM replacements. -- Doctor

Dear Doctor: I need to resolve a dispute I'm having with someone about manual transmissions. I have been driving five-speed transmissions for 26 years and have always skipped gears when shifting. I do not believe it causes any harm to the transmission. I remember reading a pamphlet from Sunoco many years ago, and they recommended skipping gears. Is this OK? -- Patrick

Dear Patrick: Great question. Skipping gears will not cause any issues, unless you cause the engine to jerk from skipping two gears instead of just one gear at a time. You should always start off in first gear, as well as always put the transmission in neutral and your foot off the clutch at stop lights. -- Doctor

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Dear Doctor: My 2000 Ford Taurus shift cable broke. I can't understand how this happened since there was no rust and the car only has 65,000 miles on it. Please advise. -- Tony

Dear Tony: This is a normal condition, as your car is 14 years old. The shift cable is a one-piece internal cable with an eyelet hole connection at either end. Car parts -- as anything mechanical -- will wear out over time. -- Doctor

Dear Doctor: The automatic climate control will not work on my Expedition. As I increase the fan manually to full speed, the heating and A/C work fine, however, it only blows at full strength, nothing less. Any thoughts? -- Ray

Dear Ray: This is a common fault on many vehicles. The fan speed is controlled by voltage going to it. The voltage is controlled via the  heater switch to the heater blower motor resistor that actually lowers the voltage to the heater motor. The blower resistor is located in the heater box and is cooled by the moving air in the heater box. The blower resistor gets hot and is subject to dampness and poor connections. Ford has available both resistors and the small pigtail wire harness, and so too do some big auto parts stores. In some rare cases the actual switch can overheat and act the same. -- Doctor.

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