Transmission not shifting properly?

Welcome to 2CarPros.

Most certainly. The VSS can be the entire problem. However, before just replacing it, have you checked for diagnostic trouble codes? Usually a bad sensor will set a code indicating the failure.

Pic 1 shows VSS location.

If you check the VSS and it's good, continue to the next test.

If you get a code 16, there is most likely an issue with the VSS buffer. Here are the directions for testing it.

CIRCUIT DESCRIPTION
This DTC concerns a loss of 2002 pulses per mile to the PCM terminal "F13." This may be caused by loss of power to the Vehicle Speed Sensor (VSS) buffer or an open or grounded signal line.

DTC 16 WILL SET WHEN
Less than 2 mph.
1400 to 5000 rpm.
Throttle angle less than 2%.
ECT greater than 60°C (140°F).
MAP less than or equal to 27 kPa.
CKT 1716 open or grounded.
All conditions must be met for 2 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
None.

DTC 16 WILL CLEAR WHEN
Conditions for fault are no longer present and Tech 1 "clear DTCs" function is used or 50 ignition switch keycycles have passed with no further faults or ignition switch is turned "OFF" and battery feed voltage is removed for 10 seconds.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This tests for B+ at VSS buffer.

2. This tests for proper ground path for vehicle speed sensor signal buffer.

3. This tests for vehicle speed sensor signal buffer signal to PCM.

4. This test checks for faulty connections and a faulty VSS buffer.

DIAGNOSTIC AIDS
Check connections at VSS buffer and PCM. Refer to appropriate trouble codes if DTC 24 or DTC 72 is also set.

The remaining pics are a flow chart for checking this issue. The last two pics show location of the VSS buffer.

Let me know if this helps or if you have other questions

Joe

Scan the transmission control module for codes. There were a lot of these that had valve body updates to the transmission. These guides can help us

https://www.2carpros.com/articles/automatic-transmission-problems

and

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Please run down these guides and report back.

Hi,

It sounds like the wire is related to the signal from the vehicle speed sensor. (VSS). That will cause the transmission shifting issue and the speedo as well.

Glad to hear you got it fixed, Let us know if you have questions in the future.

Take care,
Joe

Okay. The no third or fourth is most likely caused by the wheel speed sensor code so we need to fix that. I attached the test for this code. If the transmission is new and the sensor is new then more than likely you have a wiring issue which you should find following this test.

Let me know if you have questions as you work through it. Thanks

Okay. I attached those codes as well. Yes. You start with the flow chart and the second page is the wiring diagram for this code. Then the last page is a description. I would read the third page so you are familiar with it but it looks like you may have one issue causing all three of these so I would start with one of the speed sensor codes and fix that one. Then I bet the others will not return either. However, if they do, just move onto to it. Worse case scenario you have three separate issues but I highly doubt that.

Hello,

It sounds like the engine has low vacuum due it a clogged catalytic converter. To be sure here is a guide so you can test it to confirm the issue:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Also we should run the codes.

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Please run down these guides and report back.

DTC 24 - Vehicle Speed Sensor error (open circuit or no activity) Does the speedometer work? If not check the speed sensor on the back of the T-Case for bad/damaged wiring. Or a defective speed sensor.

DTC 61 - This one comes up with three possible definitions. The one GM lists as applicable to your truck is a bad BPMV (Brake Pressure Modulator Valve) (for DTCs 61/62/63 all the same solution, replace the valve.

DTC 73: Pressure Control Solenoid (PCS) Circuit Current Error (Force Motor Circuit)

Circuit Description: The pressure control solenoid is a TCM-controlled device used to regulate transmission line pressure. The TCM compares TP voltage, engine rpm and other inputs to determine the appropriate line pressure of a given load. The TCM will regulate the pressure by applying a varying amperage to the pressure control solenoid.
The applied amperage can vary from 0.1 to 1.1 amp. The TCM then monitors the amperage on the return circuit.

DTC 73 Will Set if - The return amperage varies greater than 0.16 amps from the commanded amperage.
All conditions are met for 1 second.

I would start with the speed sensor as it tells the system when and how to shift and may be causing the DTC73 because it does not shift.

Not sure how solenoid B could be stuck on, The 4L60 only has one solenoid and it locks the convertor clutch.
Un plug it and see if you can shift now.

Good afternoon,

There is a governor in the transmission that controls the shifting. It is a common failure for this issue.

Roy

1. Raise and support vehicle
2. If necessary, remove exhaust system.
3. Remove governor cover from case using extreme care not to damage cover. If cover is damaged, it should be replaced.
4. Remove governor.
5. Reverse procedure to install and check fluid level.