P1893

What it means

P1893 on a Buick is a GM-specific code meaning the Engine Torque Signal has been seen at a low voltage. This is a signal that the engine control module sends to the transmission control side so shift timing and line pressure can be matched to engine load. The code sets when the receiving control unit sees the signal circuit sitting below its expected voltage range.

Symptoms

• Harsh, delayed or flared gear changes
• Transmission stuck in one gear or in a limp-home mode
• Malfunction indicator lamp or transmission warning lamp on
• Change in shift feel or firmness under load
• Poor fuel economy or reduced performance

Possible causes

• Damaged, chafed or shorted-to-ground wiring in the engine torque signal circuit between the engine and transmission control unitslikely
• Corroded, loose or pushed-out pins in the engine control module or transmission control module connectorslikely
• Open circuit or high resistance in the signal wire or in a related ground or power supplypossible
• Fault in the engine control module output driver for the torque signalpossible
• Fault in the transmission control module input circuitrare
• Outdated or faulty control module calibration, where a manufacturer bulletin lists it as a known cause for the specific modelrare

How to diagnose

1. Read all stored and pending codes and note the freeze frame data, checking for other engine or transmission codes that point to a shared cause
2. Check battery condition and charging voltage, as low system voltage can upset module signals
3. Visually inspect the wiring harness between the engine and transmission control units for chafing, heat damage, rubbing points and water ingress
4. Inspect the relevant connectors for corrosion, bent or loose pins and poor terminal tension
5. Look up the wiring diagram for your model and engine to identify the torque signal circuit, as routing and module layout vary
6. Check the signal wire for short to ground, open circuit and resistance with the connectors disconnected and ignition off
7. Check the related power and ground supplies at both modules for good voltage and low resistance
8. Clear the code and road test while watching live data to see whether the signal returns and the fault repeats

How to fix

• Repair or replace damaged wiring in the torque signal circuit, using proper soldered and sealed joints
• Clean or replace corroded connectors and terminals, and restore correct pin tension
• Repair faulty ground or power supply connections to the control modules
• Replace or repair a confirmed faulty control module, then carry out any required programming or setup for your model
• Update the control module calibration only if a manufacturer service bulletin identifies it as the fix for your vehicle

Can I keep driving?

This code for other makes

• P1893CadillacEngine Torque Signal Low Voltage
• P1893ChevroletEngine Torque Signal Low Voltage
• P1893GMEngine Torque Signal Low Voltage
• P1893GMCEngine Torque Signal Low Voltage
• P1893OldsmobileEngine Torque Signal Low Voltage
• P1893SaturnEngine Torque Signal Low Voltage

Nearby codes

• P1892BuickThrottle Position Sensor PWM Signal High
• P1894BuickEngine Torque Signal High Voltage