August 2003 Archives - Transmission Digest
The Road to Hell is Paved With Good Intentions

Dynamic emissions testing on chassis dynamometers can be disastrous for all-wheel-drive transfer cases

In my distant youth, my mother often said to me, “The road to Hell is paved with good intentions.” During those years it never dawned on me how true those words were, but as I aged it became clear how smart my mother really was.

Figuring Out the Fuso

We have had some confusion on the ATSG help lines in reference to 1999 and later Mitsubishi Fuso tilt-cab medium-duty trucks equipped with the Aisin Seiki.

The first problem is, how do I get codes out of these trucks? Since aftermarket scan tools do not communicate with these trucks, data is not available and code retrieval must be done via the flash-code method. That means that a certain procedure must be performed, after which a light somewhere on the dash will flash a code pattern. The illustration in Figure 1 shows the locations of the diagnosis switch and the memory-clear switch, both of which are single-pin connectors.

Coolers and Contaminants

Most of us have been battling cooler and contamination issues for years. We may not realize it, nor care to look for it, but it does manage to rear its ugly head.

First we need to look at the sources. Mike Steen (technical director at Certified Transmission) has spent considerable time on finding these sources. Along the way, I have found a few as well. Hung valves and stuck governors have plagued us for years. We thought the contaminants came from coolers. We bought flushers and flushed coolers, and the problem went away – well, not quite. We still have problems.

The 4T65-E: ‘Slip-Sliding Away’

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.

August 2003 Issue

Issue Summary:

Vehicles equipped with the RE4RO1A transmission may exhibit a 2nd gear start, with no first or fourth gear.

Mitsubishi Fuso trucks have a diagnostic lamp that will flash if the automatic-transmission control unit detects a fault. We cover procedures for retrieving and clearing codes on 1988-94 and 1995 and later models.