P1893

What it means

P1893 on an Oldsmobile means the transmission control module saw the engine torque signal voltage fall below its expected range. This signal normally comes from the engine control module and tells the transmission how much torque the engine is making so it can set shift timing and line pressure. A low voltage reading suggests a fault in the signal circuit or in one of the modules involved.

Symptoms

• Harsh or abrupt gear changes
• Delayed or flared shifts
• Transmission stuck in one gear or in limp mode
• Check engine or service transmission warning light on
• Poor or inconsistent fuel economy
• Torque converter clutch not engaging properly

Possible causes

• Open circuit, short to ground or chafed wiring in the engine torque signal wire between the engine and transmission control moduleslikely
• Corroded, loose or pushed-out pins in the engine control module or transmission control module connectorslikely
• Poor power or earth supply to the engine or transmission control modulepossible
• Fault in the engine control module output driver for the torque signalpossible
• Fault inside the transmission control module or its signal input circuitpossible
• Other engine fault codes affecting torque calculation, such as throttle or air flow sensor faultsrare

How to diagnose

1. Read all stored codes and freeze frame data, and note any engine or transmission codes set at the same time
2. Check for related technical bulletins and the wiring diagram for the specific model and engine, as the signal routing varies
3. Inspect the wiring harness between the engine and transmission control modules for chafing, heat damage, rubbing and previous repairs
4. Check the connectors at both modules for corrosion, bent or loose pins and water ingress
5. Check battery condition, charging voltage, and the power and earth supplies to both modules
6. With the ignition on, measure the torque signal circuit for continuity, short to ground and expected voltage against the wiring diagram
7. Monitor the torque signal value on live data while varying engine load and compare it with the engine control module's reported torque
8. Clear the code and road test to see if it returns, only after repairs, to confirm the fix

How to fix

• Repair or replace damaged wiring in the torque signal circuit
• Clean, repair or replace corroded or damaged connectors and terminals
• Restore good power and earth connections to the control modules
• Repair or replace the engine control module if its torque output is confirmed faulty
• Repair or replace the transmission control module if the input circuit is confirmed faulty, then have it programmed as required
• Fix any related engine codes that affect the torque calculation

Can I keep driving?

This code for other makes

• P1893BuickEngine Torque Signal Low Voltage
• P1893CadillacEngine Torque Signal Low Voltage
• P1893ChevroletEngine Torque Signal Low Voltage
• P1893GMEngine Torque Signal Low Voltage
• P1893GMCEngine Torque Signal Low Voltage
• P1893SaturnEngine Torque Signal Low Voltage

Nearby codes

• P1892OldsmobileThrottle Position Sensor PWM Signal High
• P1894OldsmobileEngine Torque Signal High Voltage