Mechanics

CHEVROLET CHEYENNE WIRING PROBLEM

1996 Chevrolet Cheyenne • 600,000 miles

I code p1886 and p1864 and p1860 what DO these code means.









Avatar
Guest
December 23, 2012.



1886
CIRCUIT DESCRIPTION
The 3-2 Shift Solenoid Valve Assembly (3-2 SS Valve Assy.) Is a normally-closed, 3-port, on/off device that controls the 3-2 downshift. The solenoid attaches to the control valve body within the transmission. The solenoid receives ignition voltage through circuit 1020. The Vehicle Control Module (VCM) controls the solenoid by providing a ground path on circuit 687. During a 3-2 downshift, the 2-4 band applies as the 3-4 clutch releases. The VCM varies the timing between the 3-4 clutch release and the 2-4 band apply depending on the vehicle speed and the throttle position.

When the VCM detects a continuous open or short to ground in the 3-2 SS Valve Assy. Circuit or the 3-2 SS Valve Assy, then DTC P1886 sets. DTC P1886 is a type A DTC.

CONDITIONS FOR SETTING THE DTC

The system voltage is 10-17 volts.
The engine is running.
All of the above conditions are met for 5 seconds, and either of the following fail conditions occurs for 5 seconds: The VCM commands the solenoid ON and the voltage remains high (B+).
The VCM commands the solenoid OFF and the voltage remains low (0 volts).
ACTION TAKEN WHEN THE DTC SETS

The VCM commands a soft landing to third gear.
The VCM commands maximum line pressure.
The VCM freezes shift adapts from being updated.
The VCM inhibits TCC engagement.
The VCM inhibits 4th gear if the transmission is in hot mode.
The VCM illuminates the Malfunction Indicator Lamp (MIL).
CONDITIONS FOR CLEARING THE MIL/DTC

The VCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported.
The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM.
DIAGNOSTIC AIDS

Inspect the wiring for poor electrical connections at the VCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look for the following conditions: A bent terminal.
A backed out terminal.
A damaged terminal.
Poor terminal tension.
A chafed wire.
A broken wire inside the insulation.
When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.
TEST DESCRIPTION
The item numbers below refer to the step numbers on the diagnostic chart.

This Step tests the ability of the VCM to control the solenoid.
This Step tests for voltage to the solenoid.
This Step tests the ability of the VCM and the wiring to control the ground circuit.
This Step measures the resistance of the Automatic Transmission Wiring Harness Assembly, and the 3-2 SS Valve Assy.
1864
CIRCUIT DESCRIPTION
The Torque Converter Clutch Solenoid Valve (TCC Sol. Valve) is an electrical device used with the TCC PWM Sol. Valve in order to control the fluid acting on the Torque Converter Clutch (TCC) valve. The TCC valve controls TCC application and release. The solenoid is a normally-open, ON/OFF device. The TCC Sol. Valve attaches to the transmission case assembly extending into the pump cover. The Vehicle Control Module (VCM) monitors the Throttle Position (TP) voltage, the vehicle speed, and other inputs in order to determine when to energize the TCC Sol. Valve. The TCC Sol. Valve receives ignition voltage on circuit 1020. The VCM controls the solenoid by providing the ground path through circuit 422.

When the VCM detects a continuous open or a short to ground in the TCC Sol. Valve circuit or in the TCC Sol. Valve, then DTC P1864 sets. DTC P1864 is a type A DTC.

CONDITIONS FOR SETTING THE DTC

The system voltage is 10-17 volts.
The engine is running.
The VCM commands first gear only.
All of the above conditions are met for 5 seconds and either of the following fail conditions occurs for 5 seconds: The VCM commands the solenoid ON and the voltage remains high (B+).
The VCM commands the solenoid OFF and the voltage remains low (0 volt).
ACTION TAKEN WHEN THE DTC SETS

The VCM inhibits TCC engagement.
The VCM inhibits 4th gear if the transmission is in hot mode.
The VCM freezes shift adapts from being updated.
The VCM commands maximum line pressure.
The VCM illuminates the Malfunction Indicator Lamp (MIL).
CONDITIONS FOR CLEARING THE MIL/DTC

The VCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported.
The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM.
DIAGNOSTIC AIDS

Inspect the wiring for poor electrical connections at the VCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look for the following conditions: A bent terminal.
A backed out terminal.
A damaged terminal.
Poor terminal tension.
A chafed wire.
A broken wire inside the insulation.
When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.
With the TCC engaged, the TCC slip speed should be -20 to +20 RPM.
A short to ground in the TCC Sol. Valve circuit may also set a TCC Stuck On DTC P0742.
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic chart.

This Step tests for voltage to the solenoid.
This Step tests the ability of the VCM and wiring to control the ground circuit.
This Step tests the resistance of the TCC Sol. Valve and the Automatic Transmission Wiring Harness Assembly.
1860
CIRCUIT DESCRIPTION
The Torque Convener Clutch Pulse Width Modulation Solenoid Valve (TCC PWM Sol. Valve) controls the fluid acting on the convener clutch valve. The converter clutch valve controls the Torque Converter Clutch (TCC) application and release. The solenoid attaches to the control valve body within the transmission. The solenoid receives ignition voltage through circuit 1020. The Vehicle Control Module (VCM) controls the solenoid by providing a ground path on circuit 418. Current flows through the solenoid coil according to the duty cycle (percentage of ON and OFF time). The TCC PWM Sol. Valve provides a smooth engagement of the TCC by operating during a duty cycle percent of ON time. When the VCM detects a continuous open or short to ground in the TCC PWM Sol. Valve circuit or the TCC PWM Sol. Valve, then DTC P1860 sets. DTC P1860 is a type A DTC.

CONDITIONS FOR SETTING THE DTC

The system voltage is 10-17 volts.
The engine is running.
The VCM commands first gear.
All of the above conditions are met for 5 seconds and either of the following fail conditions occurs for 5 seconds: The VCM commands the solenoid ON (90%) and the voltage remains high (B+).
The VCM commands the solenoid OFF (0%) and the voltage remains low (0 volt).
ACTION TAKEN WHEN THE DTC SETS

The VCM inhibits TCC engagement.
The VCM inhibits 4th gear if the transmission is in hot mode.
The VCM freezes shift adapts from being updated.
The VCM illuminates the Malfunction Indicator Lamp (MIL).
CONDITIONS FOR CLEARING THE MIL/DTC

The VCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported.
The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM.
DIAGNOSTIC AIDS

Inspect the wiring for poor electrical connections at the VCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look for the following conditions: A bent terminal.
A backed out terminal.
A damaged terminal.
Poor terminal tension.
A chafed wire.
A broken wire inside the insulation.
When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic chart.

This Step tests for voltage to the solenoid.
This Step tests the ability of the VCM and wiring to control the ground circuit.
This Step tests the resistance of the TCC PWM Sol. Valve and the Automatic Transmission Wiring Harness Assembly.

ASEMaster6371
Dec 23, 2012.