Wayne Colonna, Author at Transmission Digest - Page 12 of 29
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CVT 7 Troubles

The CVT 7 used in Mitsubishi and Nissan vehicles (Figure 1) is unique in that between the pulley assembly and the differential is a planetary gear set controlled by a reverse brake, a low brake and a high clutch.

Suburu 4AT Phase ll Version ll Control and Valve Body Changes

Sometime at the beginning of the 2004 model year, Subaru redesigned the 4AT Phase ll Control system that placed the transfer clutch control solenoid into the valve body. The new design valve body (referred to as Version II) contained 3 clutch control solenoids, 2 brake control solenoids, a TCC and pressure control solenoid (Figure 1).

Mazda’s SkyActiv-Drive 6-speed automatic unit: Magnet is Loaded with Metal

The progressive development of Mazda’s “SkyActiv®” engine and transmission has resulted in an engine that should be available in 2019 called the “SkyActiv-X.” The name SkyActiv given to this drivetrain reflects their back-casting developing method. They started with what they wanted to achieve regardless of how impossible it may seem, and work their way backwards to identify what made that goal seem impossible.

Is it a Bad Computer?

A 6T40 in a 2011 Chevy Malibu comes in to R.C. Trans and Repair in failsafe with a hard code P0601: Transmission Control Module (TCM) Read Only Memory (ROM). This code is straightforward. Verifying power and grounds to the TECHM are the initial checks to make. Once verified, replacing the computer would be a safe repair. Such was the case with R.C. Trans and Repair.

When it is Broken

Planetary gear sets and their operation are unappealing for many. Know what is turning and what is holding for each gear can challenge one’s thinking. Particularly so when there are 10 speeds and 3 planetary gear sets involved. I actually enjoy pushing my mind to visualize powerflow and indeed, it can be challenging at times. But it sure does go a long way when trying to isolate a noise problem.

Very Odd Issues

Wayne Colonna illustrates the odd issues that pop up with valve body bolt lengths with an example of Toyota’s U660.

An Inflated Story about Erratic Shifting

After a wide-open throttle forced downshift and then coming to a stop, the vehicle would take off in third or fourth gear. A scan tool confirmed that the wrong gear starts were commanded by the TCM. The transmission would upshift from third or fourth gear to fifth and sixth gears.

The P0763 Headache

A call came in to ATSG’s technical help line concerning a 2009 Kia Borrego with a 3.8L engine using a 5-speed RWD transmission called the A5SR2. This transmission is very similar to the Subaru 5AT transmission, a derivative of Nissan’s RE5R05A transmission. Mounted on top of the valve body are the solenoids, a sub-ROM and pressure switch frame assembly.

An ECU Dilemma

A 2009 Toyota Corolla LE with a 1.8L engine and a U341E transmission arrives to a shop with code P2757 Torque Converter Clutch Pressure Control Solenoid Performance (SLU Solenoid) Malfunction stored. The unit was removed and overhauled with a new SLU solenoid and a replacement torque converter. When it was tested, the car seemed to be working well but the Malfunction Indicator Lamp came on after reaching highway speed.

No Shim and a Short

Lorenzo Ortiz from Phillips Transmission had a 2005 Acura TSX with the MCTA five-speed transmission come into his shop for repairs. After it was repaired and installed into the vehicle, it had a new problem. The car would not start. The immobilizer lamp was flashing and the scan tool could not communicate with the engine control module, yet all other modules would communicate.

A Clever Variable Cylinder Management Fix

As quiet as the drive may be, this technology has turned into big headache for both the manufacturer and the vehicle owner. This system is known to have the potential for misfires, high oil consumption fouling the plugs, repeated failure of the motor mounts and damage to the torque converter. In fact, the 2015 ATSG seminar covered a scenario where VCM activation can be misinterpreted as a torque converter shutter.

A Sudden No Move

It’s always unsettling when a transmission comes back after the customer has had it for only an hour; especially when it came back on a hook. Such was the case at a local transmission shop with a 42RE transmission.