Message on 96 Caddilac Deville Transmission Control Module

The body control system consists of the following 3 modules:
• The Dash Integration Module (DIM)
• The Instrument Panel Module (IPM)
• The Rear Integration Module (RIM)
Each of the 3 body control modules integrate a number of functional systems under the control of a single module. Each module is connected to the Class 2 serial data circuit, many of the control functions are implemented by Class 2 messages.

Plus they would need to be programmed . Dealer only .

If you have an engine support to hold the engine in place while the transmission is removed, it is easier to just remove the transmission.

PRNDL Display
The instrument panel cluster (IPC) displays the selected gear position as determined by the powertrain control module (PCM). The IPC receives a class 2 message from the PCM indicating the gear position. The PRNDL display blanks if:
• The PCM detects a malfunction in the transmission range switch circuit.
• The IPC receives a class 2 message indicating the park position and the column park switch indicates a position other than park, open input.
• The IPC detects a loss of class 2 communications with the PCM.

Could be the transmission range sensor . Testing would need to be done , hooking up a scan tool ! Doing electrical testing etc...

Whenever this warning light or any other stays on in the dash it is indicating that the systems control module (or the system sensor in the case of lights like low oil pressure, door open indicators etc.) has detected a fault, it then disables the system (this applies to ABS,TCS, TCM, SRS, TPMS and BCM faults and others) as long as the light is on. You must now have the dealer hook up a special electronic diagnostic tool and "scan" the system for the fault code that is stored for the problem(s)

Legend of Abbreviations. ABS Anti-lock brake system. TCS Traction control system, TCM Transmission control module, SRS Supplemental restraint system, BCM Body control module. TPMS Tire Pressure Monitor System

Faulty ignition control module.

Whenever this warning light or any other stays on in the dash it is indicating that the systems control module (or the system sensor in the case of lights like low oil pressure, door open indicators etc.) has detected a fault, it then disables the system (this applies to ABS,TCS, TCM, SRS and BCM faults and others) as long as the light is on. You must now have the dealer hook up a special electronic diagnostic tool and "scan" the system for the fault code that is stored for the problem(s)

Legend of Abbreviations. ABS Antilock brake system.TCS Traction control system, TCM Transmission control module, SRS Supplemental restraint system, BCM Body control module

With the instrument cluster pulled ,but still connected to electrical connector , Check B+ voltage an ground's . Loaded circuit testing , do you know what that is ? Video's on youtube .An do you know where the gauges get there info. from ? The instrument cluster is hooked to the class 2 serial data network , this is a communication network for the control modules . PCM / ECM - engine computer , BCM - body control module , SRS , air bag module , ABS , etc.... They all share info. on this network .
Fuel Gauge
The fuel gauge is an analog device that is located in the instrument cluster. The instrument cluster operates the fuel gauge by the class 2 serial data messages from the VCM/PCM. The fuel gauge indicates the quantity of fuel in the tank when the ignition switch is in the RUN position. When the ignition switch is turned to the OFF, LOCK, START, or ACC position, the pointer may come to rest at any position.
The VCM/PCM measures voltage from a variable resistor inside the fuel tank that is controlled by a float. When the fuel tank is full and the ignition switch is in the RUN position, the resistance is high. The VCM/PCM interprets this signal and sends a message to the instrument cluster indicating the percentage of fuel in the tank over the class 2 serial data line. The fuel gauge indicator then moves to the maximum position or FULL on the gauge face. When the fuel tank is empty, resistance is low. The VCM/PCM interprets this signal and sends a class 2 serial data message to the instrument cluster. The fuel gauge indicator then moves to the minimum position or EMPTY on the gauge face. Failures detected by the PCM/VCM in the fuel gauge signal sends the gauge to EMPTY.

PRNDL Indicator (Park Reverse Neutral Drive Low)
The PRNDL display is a class 2 serial data message to the instrument cluster from the PCM/VCM. The PRNDL display is a vacuum florescent (VF) display which displays the fixed gear position of P, R, N, D, 3, 2, 1 surrounded by a moveable square flag in order to indicate the selected gear position. The position of the moveable square flag is sent to the instrument cluster from the transmission range switch over the class 2 serial data line. The transmission range switch and the neutral safety back up (NSBU) switch operate separately but are incorporated into one part. If the vehicle is equipped with a column shift steering column it will also have a park position switch. The park position switch (if equipped) must also be CLOSED in order for the instrument cluster to display the PARK position. Since the system is entirely electronic, there is not any internal adjustment. The PRNDL display will operate as follows:
• The PRNDL display will display the PARK position when a class 2 serial data message is received from the PCM/VCM indicating the transmission is in the PARK position and for vehicles which have a column shift on the steering column, the park position switch must also be CLOSED (low input).
• The PRNDL display will display a gear position if a class 2 serial data message from the PCM/VCM is received indicating the gear position of the transmission.
• The moveable square flag will not appear on the instrument cluster in order to show no gear was selected when the instrument cluster does not receive a class 2 serial data message from the PCM/VCM within 5 seconds of entering the UNLOCK or the RUN position.
Refer to Engine Controls or Transmission/Transaxle for more information about the PRNDL indicator.


Hooking up a GM tech 2 scan tool an checking for DTC'S - diagnostic trouble code's would be a good first step in the diagnostic procedure .
Data Link Communications Circuit Description
The serial data line is the means by which the microprocessor controlled modules in the vehicle communicate with other control modules and the scan tool.
The control modules on the class 2 data line are as follows:
• Body control module (BCM)
• Instrument cluster (IPC)
• Automatic transfer case (ATC) control module
• Vehicle control module (VCM)
• Powertrain control module (PCM)
• Inflatable restraint sensing and diagnostic module (SDM)
• Electronic Brake Control Module (EBCM)
• Suspension Control Module (SCM)
• HVAC Control Module

Your best bet mite be to take it to a qualified repair shop .

po700 Transmission Control Module Requested Malfunction Indicator Lamp Illumination, p1779Engine Torque Delivered To Transmission Control Module, Signal p1780 Engine Torque Reduction Signal Circuit p1795 Controller Area Network Bus Throttle Body Position

each wheel has it's own sensor and it's an integral part of the wheel hub. if you have a problem, the computer will tell you which wheel is the problem and you will have to change that hub. not a hard fix, but the fronts take more time bcuz of the drive axle.

check the brake fluid and make sure caliber is full of fluid. mine said that and it was because fluid was low.