Recently a 2006 Chevrolet Impala came into one of our retail locations with a surge complaint while cruising on the highway between 60-65 mph. I drove the vehicle with the customer to verify the concern and was able to duplicate the circumstances in which the vehicle acted up. While watching the tachometer I noted that there was a noticeable 150-200 rpm surge while TCC was applied. It felt like a typical TCC surge as a result from a leak in the TCC regulator circuit, so additional diagnostic steps were in order. We discussed this with the customer, and he authorized the additional time. At this point I was fairly convinced that we were going to need to go inside the unit.
Let’s start with the valve body. Unfortunately, there are no casting numbers on the 4T65-E valve body for quick identification. The four most-common 4T65-E valve bodies are the early GM, late GM, early Volvo and late Volvo. There are more than four variations, and they can be found during the crossover years of 2002 and 2003. There are four questions that you need to answer to properly identify the valve body.
The example used here is a 1998 Oldsmobile Intrigue 3.8L with a 4T65-E transaxle that has a P0753 electrical code – 1-2 shift solenoid circuit – stored in the PCM; no other DTCs are present. The code will not set until the 1-2 solenoid is commanded to turn on. Now we have all seen the diagnostic flow chart for this code. No matter which repair-service publication you use they are all basically the same: Check resistance from here to here and here to here, from there to there and from here to ground, blah blah blah; I think you know what I mean. Then we print off a wiring diagram so we know what to look at.
The 4T65-E and 4L30-E share a number of issues related to the torque-converter clutch (TCC). Both transmissions are notorious for their TCC-application and shudder problems. A root-cause analysis of each application yielded similar results.
In this article I’ll share with you some of the differences that I have found between the 4T65-E “Tiptronic” and the typical “non-Tiptronic” 4T65-E.
This particular tech call was the usual 4T60-E or 4T65-E transaxle with the code P0741, “Torque Converter Clutch System Stuck Off.” It began as so many times before with the normal question, “Was this unit just rebuilt or is it coming back with this problem?” The next question was, “What repairs have you done to correct this problem?”
The 4T65-E was introduced in 1997 in several vehicles equipped with the supercharged 3.8-liter engine, and some non-supercharged 3.4- and 3.8-liter engines. It was considered to be the big brother to the 4T60-E transaxle.
With a basic understanding of TAPS, the Transmission Adaptive Pressure System, covered in last month’s article, we will now try to tap into the Steady State Adapt System and what its data can tell us. Not all scan tools provide steady-state data, but I’m convinced that this information is a real help in diagnosing problems in the later GM units. Data for the examples I used in these articles was recorded on either my GM Tech2 or my Mastertech. All the units in the examples shown below are 4T65-Es.
TAPS is one of the latest acronyms to join the list. It stands for transmission adaptive pressure systems, and it is used both for shift adapts, which establish pressure control during the shift, and for steady-state pressure control, the adapting-pressure requirements for a given gear after the shift is completed.
Incorrectly installed 4T65-E internal mode switch causes shift problems
I got a call from a technician who was working on a 4T65-E. It seems that after the freshly rebuilt transmission was re-installed, the car would not start in park or neutral and the transmission would make a wrong-gear start and shift only once. I came to find out that this was not an original problem, which means it was created during the repair process.
Three to six months after you overhaul a 4T65-E transaxle, the vehicle may come back with a code, either P0730 (incorrect/undefined gear ratio) or P1811 (maximum adapt and long shift).
Generally, code P0730 occurs immediately after installation of a transaxle with an incorrect ratio. This could mean that either an exchange unit with an incorrect ratio was installed or incorrect sprockets and/or final drive was used during rebuild in the shop.
I don’t think I have anything weird for you this month, just some differences in 4T65-E applications requiring special overhaul-kit items that you need to be aware of when it’s on your bench.