P1893

What it means

P1893 on a GMC means the transmission control side has seen the engine torque signal sitting at a low voltage, below the range it expects. This signal is sent from the engine control module to the transmission control module (or the combined powertrain module) and is used to manage shift feel and line pressure. The exact signal type and how it is carried depends on the model, engine and year, so check the specific wiring diagram.

Symptoms

• Harsh, delayed or soft gearshifts
• Transmission stuck in one gear or in a limp mode
• Check engine light or service transmission warning on
• Poor or erratic shift quality under load
• Reduced power or hesitation on acceleration

Possible causes

• Wiring fault on the torque signal circuit, such as a short to ground, chafing or open circuit between the engine and transmission controllerslikely
• Corroded, loose or pushed-out terminals at the engine control module or transmission control module connectorslikely
• Fault in the engine control module's torque signal output driverpossible
• Fault in the transmission control module's signal inputpossible
• Related engine sensor faults (for example throttle or air flow) causing a poor torque calculationpossible
• Outdated control unit software where a known fault is documented for that modelrare

How to diagnose

1. Read all stored and pending codes and record the freeze frame data, noting any engine or transmission codes set alongside P1893
2. Check for technical service bulletins and software updates relevant to the specific model and engine
3. Visually inspect the wiring harness between the engine and transmission controllers for chafing, heat damage, fluid contamination and previous repairs
4. Inspect and reseat the connectors at both control units, looking for bent, corroded or loose terminals
5. Use the wiring diagram to identify the torque signal circuit for the vehicle, then check it for continuity and for shorts to ground with the connectors disconnected
6. With the ignition on, check the signal voltage and compare it with the specification for that model
7. Check the battery condition and the grounds and supply feeds to both control units
8. If wiring and power are sound, test the signal output and input of the controllers following the manufacturer procedure

How to fix

• Repair or replace the damaged section of wiring on the torque signal circuit
• Clean, repair or replace faulty connector terminals and secure the connectors
• Repair poor grounds or power supply faults to the control units
• Fix any related engine sensor faults that affect the torque calculation
• Update the control unit software where a known fault is documented, or replace and program a confirmed faulty control module

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
• P1893OldsmobileEngine Torque Signal Low Voltage
• P1893SaturnEngine Torque Signal Low Voltage

Nearby codes

• P1892GMCThrottle Position Sensor PWM Signal High
• P1894GMCEngine Torque Signal High Voltage