Technically Speaking
- Subject: Cross-connection of input- and output-speed sensors
- Unit: Chrysler 42RLE
- Essential Reading: Rebuilder, Diagnostician, R & R
- Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor
This article, yet another pointing out cross-connect scenarios, has to do with the 42RLE input-shaft and output-shaft speed sensors.
The main harness is secured to the top of the transmission (Figure 1). When the harness is secured properly the cross-connecting of these two sensors becomes difficult if not impossible to do.
During transmission removal the harness’s lock-down pin is popped out of the case, properly freeing the harness from the transmission (Figure 2). Forgetting to secure this harness during installation allows for the cross-connection to occur. When this self-inflicted injury occurs, the transmission will shuttle-shift between first and second as soon as it is placed into drive. Before you can actually drive the vehicle it will failsafe with a first-gear-ratio code and a fault-after-shift code.
In the Technically Speaking article in the November 2010 issue of Transmission Digest, I covered a similar scenario with the Nissan RE4F04B transmission. I pointed out that there is a white label on the vehicle harness behind the connector that is to be used as an identification for the revolution sensor (aka OSS) to ensure proper connection. The 42RLE does the same thing but with a yellow tag identifying the correct connector for the output-shaft speed sensor (Figure 3).
Another way to quickly identify this error is by looking at the speed-sensor parameters in a scan tool. When the connectors are cross-connected, the OSS will read rpm while the ISS will remain at 0 rpm immediately upon startup – a sure indicator that these two sensors are reverse-connected. Heads up; this error has occurred with the 41TE as well.
Many thanks to Ralph Abraham from Alonso’s Transmissions in Miami.
