Auto Transmission Troubleshooting
Engine Brakes Drivetrain Auto Repair and Car Diagnose CD-ROM For Repair
Hard Shifting when troubleshoot cars Hot
Symptom: Transmission shifts smoothly when cold or warm; however, when it has
warmed up sufficiently, it sometimes auto repair shifts hard with a jarring bump or kick. When it
cools down a bit, it shifts fine again.
Possible cause: The transmission troubleshoot cars fluid temperature sensor may be faulty. This
sensor adjusts the accumulator pressure which in turn adjusts the smoothness of the
clutch engagement. Cold fluid is auto repair thicker and flows slower, while hot fluid flows faster.
The accumulator therefore has to adjust the amount of fluid flow accordingly. Therefore
if the sensor is faulty, it might report that the fluid is cold when it is actually hot.
A painless way to fix a "bad" transmission!
When you change your transmission fluid, always use the recommended (in the manual) fluid.
Don't just assume your mechanic or dealer knows what fluid to use. Ask them what they will use and make sure it's the right one. (Some auto repair people recommend watching the mechanic pour it in, and for good reason! We have been told about mechanics who said they were using 7176 when they were not. Is a transmission worth the $10 for better fluid?)
Hunting at steady speed
Symptom: When travelling at a steady speed on level ground, the transmission may
hunt (shift between gears for no real reason) with very slight throttle movement.
Possible cause: The throttle position troubleshoot cars sensor may be faulty, or it may be misaligned. I
had diagnosed mine as a bad TP sensor and it was replaced by Nissan under
warranty, however the problem auto repair still didn't go away. I then checked the alignment of the
sensor relative to the actual throttle plate position and found it was off, so the new
sensor wasn't reporting the correct throttle position and it was misinterpreting the
amount of throttle I was actually giving (it thought I was giving more throttle so it
downshifted when it didn't have to). I guess the mechanic car repair didn't align it properly.
Be aware that this is a tricky auto repair part to replace as you have to drop the transmission pan
to get at the sensor, which is attached to the troubleshoot cars bottom of the valve body. For later
model W/D21's (say '92 or '93 and up), the sensor isn't individually replaceable but you
have to replace it and the entire wiring harness to the engine compartment near the
battery. The shop manual for my '94 is incorrect auto repair in showing the sensor as a separate
part.
If you don't have any problems until you have your car serviced...what does that tell you?
Frequently, a transmission that the dealer or transmission shop says is "not repairable" can be fixed with the simple steps outlined on this page, so don't give up hope just because a mechanic or two says your transmission needs to be replaced. Don't just take out word for it. Click here to read testimonials and other readers' experiences.
Computer revision
As detailed in a technical service bulletin, 18-24-95, many issues (including the infamous "bump shift") can be troubleshoot cars resolved by updating the computer's flash ROM (where possible), and carefully going through a retraining process. Dealers can and should do this free of charge before any other work is undertaken (except of course for the transmission fluid change).
The Transmission Control Module (TCM) is another item that deserves mention. I found a TSB
indicating a flash upgrade (software?) was needed to eliminate hard/erratic shift problems after 2 dealers told me I needed a $1600 transmission troubleshoot cars rebuild. I insisted they perform the upgrade first. The TCM refused to accept the upgrade so I had them replace it (they did it under protest). Now my transmission works like new. It cost 'just' auto repair $200. Something to consider.
I got a quote of $1500 to get my LeBaron running again. When I went to get a second opinion, the guy checked the transmission with some fancy computer, switched the two transmission relays...and it works now. Now, after a replacement troubleshoot cars relay was installed (about $50) it runs like new!
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