PCM Archives - Transmission Digest
Solving electronic control problems in today’s automatic transmissions

Special tools are often needed when diagnosing transmission problems and overhauling units.

The Nightmare on Oak Street: A hunt for 4L30E electrical problems

This story begins with a 4WD 1998 Honda Passport equipped with a 3.2 V6 engine and 4L30E transmission. The shift indicator in the cluster was not functioning correctly and transmission was shifting hard. The shift indicator showed ‘P’ in Park, and ‘1’ in D3, D2, or D1. The indicator didn’t light up in any other

nightmare-1400
An accidental solution: When an issue resolves itself, but you don’t know why

Today I found myself working on a 2008 Chevy Silverado with a 4L60E transmission that wasn’t shifting correctly and whose speedometer was jumping around. After a short drive I was able to confirm the customer’s concern that the transmission had an erratic shift. I have seen faulty alternators that cause erratic speedometers, so I did

RR-Tech-September
Video: PCM Replacement

When a repair facility retains a job, it is with the hope that the necessary product is readily available. The question arises that when traditional sources and even the OEM is unable to provide a specific item what other options is there to complete the work.

Diagnosis: Do the Homework

Occasionally in diagnosing transmission problems technicians are faced with challenges that force us to look beyond the transmission control system. As vehicles become increasingly complex, it is crucial that we educate ourselves with all systems pertaining to the vehicle we are diagnosing. Many systems are tied together in one way or another and can directly

No Idle Curiosity

The car was a 2008 Chrysler Sebring with a 2.4-liter engine. She complained that there were times when she stepped on the gas and the car would just idle along. Lately, she told me, the idling had been accompanied by a blinking icon showing two bars and a lightning bolt between them. She said that when the car wouldn’t accelerate, she could turn it off, restart it, and it would be OK for an undetermined amount of time.

Proving a RAV4 PCM to Be Defective

Recently we had a 2001 Toyota AWD RAV4, with 114,000 miles on the odometer, come into the shop for transmission diagnosis and repair. It had a bind feeling on the 1-2 shift and a flare when it shifted to third, no codes and burnt fluid. Once it was in third and then fourth, it would drive fine, and the lockup also functioned properly.

Do You Speak My Language?

The local transmission shop, in an effort to eliminate a code 68, replaced the input- and output-speed sensors, 2-3 solenoid and the transmission-range pressure switch (later you will see why). It also replaced the internal harness and external connector because they where “old and fitted loose.” When the problem persisted, the local transmission shop sent the vehicle to us.

Something Is Missing!

Remember, earlier in the article I mentioned that this was a fleet vehicle. You know what happens with fleet vehicles; they borrow good working components from one vehicle and put it in the vehicle that’s not working. Now, maybe the fleet mechanic had every intention of replacing the borrowed part, but it never happened. It was forgotten, and the fleet mechanic on a different shift ran into the transmission stuck in 4th gear and sent it to this transmission shop.