1, 2 and 3 Digit Codes: 20

CODE NUMBER
Scan tool: 20
General scan tool: P1765

CODE NAME
Switched battery

CODE DESCRIPTION
Technical Description
The Transmission Control Relay is used to supply power to the solenoid pack when the transmission is in normal operating mode. When the relay is "off", no power is supplied to the solenoid pack and the transmission, is "limp-mode." The relay output is fed back to the TCM through pins 56 and 57.
Immediately after a controller reset (ignition key turned to the ".run" position or after cranking engine), the TCM verifies that the relay contacts are open by checking for no voltage at Transmission Control Relay output terminals. After this is verified, the voltage at the solenoid pack pressure switches is checked. There should be no voltage on the pressure switches at this time. The TCM then activates the relay.

Check Area
Ignition key is turned from "off" position to "run" position and/or ignition key is turned from "crank" position to "run" position. The following conditions must be met for a successful OBDII trip:
- The engine must run for more than two minutes
- The turbine speed must be greater than 600 r/min or the output speed must be greater than 400 r/min.
- If the transmission is below normal operating temperature, all forward gears must be applied for 3.5 seconds each and the transmission must be in either "park" or "neutral" for 3.5 seconds.
- If the transmission is hot, all forward gears must be applied for 1.5 seconds each and the transmission must be in either park or neutral for 1.5 seconds.
- No MIL lamp trouble codes have occurred or reoccurred.

Set Conditions
This code is set if the Transmission Control Module (TCM) senses voltage on any of the pressure switch inputs prior to the TCM energizing the relay.

Transmission Effects
Relay open limp-in mode.

Possible Causes:
- Short to battery on one or more pressure switch sense circuits
- TCM connector problem
- Defective TCM

PROBABLE CAUSE
- Malfunction of EATX relay, harness or connector between relay output TCM open or short-circuited
- Harness of connector between EATX relay output and TCM temporarily short-circuited.
- Malfunction of TCM





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