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Self-inflicted injuries part 1

Wednesday, March 20, 2013 - 09:05
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One undesirable aspect of our lives is known as “human error.” We know it happens, we may not like to admit it, but it happens. Those who do recognize that human error is inevitable, develop safeguards to prevent these errors, or at best to try catching them before they become costly.

Because no part of life is exempt from this facet of living, we know it extends into automotive repair. The problem is, either there are no safeguards to prevent mistakes or, it does not become part of diagnostics after the error has occurred. Whether you installed a remanufactured transmission, a rebuilt transmission or an exchanged unit from a salvation yard, I would like to share with you some elusive errors causing transmission malfunction. Because it is an elusive error, much wasted time is spent trying to locate the problem.

The problem being presented concerns cross-connecting connectors. Though I have written about this problem several times over the years, this article will cover several current cross connect scenarios. The idea is to recognize cross connect possibilities and tag them for proper reconnect as a preventive measure. Or, to at least be aware of its possibility should you need to diagnose the problem after the error took place.

The most serious connector cross connect I had ever encountered took place in a local shop back in the late 1990s. It was with a 1993 or ’94 Mazda 929 vehicle equipped with an R4A-EL transmission. The transmission’s Turbine Speed Sensor had been cross-connected with a heated oxygen sensor. With voltage being sent to the O2 sensor now doing a U-turn back to the transmission control unit, it took only seconds after starting the vehicle that this error became evident. Smoke billowed from every orifice of the dash assembly. Needless to say it was a very expensive error requiring the replacement of a complete harness, PCME and EC-AT Control Unit.

To our advantage, the common cross connects that typically takes place these days do not result with such catastrophic consequence. Nonetheless, they still cause an unpleasant day or days.

The most common connector cross connect occurring today has to do with a transmission called the 62TE. This 6-speed front wheel drive transmission is used in vehicles such as the Avenger, Caravan, Dart, Journey, Ram Van, Pacifica, Sebring, Town & Country, Voyager, 200 and oddly enough, the VW Routan. This transmission has three speed sensors: an Input Shaft Speed Sensor (Nt), a Transfer Shaft Speed Sensor (Nc) and an Output Shaft Speed Sensor (No). Due to their close proximity, the TSS and the OSS easily can be cross-connected, because their connectors are of the same configuration. This connector cross-connect causes erratic shifts followed by P0730 series gear ratio codes (P0731, P0732 etc.). 

All three of these sensors usually will have a dark green wire with a violet tracer in their connector. The Nc will also have a Dark Green with a Light Green Tracer wire in its connector while the No will have a Dark Green with a Brown tracer wire in its connector.

The next most common connector cross connect occurs with the Nissan Altima, Maxima, and Quest vehicles using the RE4F04B transaxle. With this transmission both the Turbine Shaft Speed Sensor (TSS) and Output Shaft Speed Sensor (OSS) are side by side, facilitating an easy cross connect mistake. This causes a no up-shift condition with a P0720 OSS code to be stored. The reason for this is that TSS is excited by the lugs on the forward clutch drum, which is held stationary in first gear. With the OSS harness connector plugged into the TSS, the TCM doesn’t receive an OSS RPM on take off preventing a shift and causing the P0720 code to set.

In part two of this Self Inflicted Injuries series, I will use these two transmissions, the 62TE and the RE4F04B as examples of using the wrong parts and what it causes.

Ford, Mercury Problems
The next occurs with 2001 and newer Ford/Mercury vehicles using the CD4E transmission (Contour, Cougar, Escape, Mariner, Mystique, Probe and ZX2). The TSS and OSS/VSS with this transmission can also be cross-connected. When it is, a speedometer reading will occur while in Park during engine rev. While driving, it will be noticed that vehicle speed is approximately 15 to 20 miles slower than what it should be. It will attempt a shift into third but suddenly downshifts back to second or first. It will then set P0730 series gear ratio codes. Usually, a Brown wire with a Light Green tracer will be seen in each of the harness connectors. The TSS will also have a White Wire with a Light Blue Tracer wire in its connector while the OSS/VSS will have Dark Blue with a Yellow tracer wire in its connector.

The least but not the last to be covered is Acura and Honda vehicles, particularly the early MDX and Odyssey vehicles (around 2001-2002).  This transmission has several external solenoids paired together with black and brown colored connectors. Shift Solenoid A and C can be cross-connected with Shift Solenoid B and the TCC solenoid. Or these solenoids can be a cross-connected with the two Clutch Pressure Control Solenoids. Just reading the various possibilities you can already imagine the mess it produces. Wrong gear starts, harsh shifts and various solenoid codes will no doubt be the complaint.

Other cross connects we has seen in the past occurs with the ISS and OSS in Chrysler/Dodge vehicles using the 41TE (A604) transmission, or GM’s 4L80-E transmission. We also have seen early Mitsubishi vehicles using the KM175 4-speed transmission having the Pulse Generators cross connected with the Shift Solenoids.

Not knowing connector cross-connect possibilities and their symptoms have lead to numerous wasted man-hours and parts. In life we have learned the negative affects produced when our wires get crossed. No different in the automotive industry and not just with automatic transmissions. I have seen for example some Kia vehicles getting the IAV cross-connected with the TPS. So it needs to be in one’s diagnostic arsenal especially if the vehicle came from another facility after giving up on what’s wrong.

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