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P1768 Acura

Diagnose and fix P1768 Acura

Fix P1768 Acura trouble code

The Acura M5DA automatic transmission in used in late 1990’s

M5DA automatic transmission

M5DA automatic transmission

Acura vehicles with the 3.5L engine. The M5DA transmission is controlled by the powertrain control module (PCM). A P1768 Acura trouble code is defined as Linear Solenoid. When the PCM detects a solenoid problem, the “D” indicator flashes.

Acura M5DA automatic transmission trouble codes

The Acura M5DA automatic transmission can set up to 12 distinct trouble codes:

P0715 Defective Mainshaft Speed Sensor causes Transaxle to jerks hard when shifting

P0720 Defective Countershaft Speed Sensor causes lock up clutch to not engage

P0730 Defective Shift Control System causes a fail to shift or transmission gets stuck in 1st or 4th gear.

P0740 Defective Lock-Up Control System causes lock up clutch to not engage OR to remain engaged resulting in unstable engine idle

P0753 Defective Shift Control Solenoid “A” causes transmission to remain in 4th gear, fails to shift

Other than 1st-4th, 2nd-4th Or 2nd-3rd Gears

P0758 Defective Shift Control Solenoid “B” causes transmission to remain in 1st or 4th gear.

P1705 Defective A/T Gear Position Switch causes lock up clutch to not engage results in failure to shift other than 2nd or 4th gears.

P1706 Defective A/T Gear Position Switch causes lock up clutch to not engage or engages and then disengages, results in failure to shift other than 2nd or 4th gears.

P1753/1 Defective Lock-Up Control Solenoid “A” causes lock up clutch to not engage resulting in unstable idle.

P1758 Defective Lock-Up Control Solenoid “B” causes lock up clutch to not engage

P1768/16 Blinks Defective Linear Solenoid causes transaxle to jerk hard when shifting and lock up clutch to not engage

P1791 Defective Vehicle Speed Sensor causes lock up clutch to not engage

Acura M5DA automatic transmission inputs

The Acura PCM receives inputs from these sensors to determine shifting

• Brake light Switch — delivers input signal to PCM, indicating vehicle braking. Brakelight switch is located on brake pedal support.

• Countershaft Speed Sensor — delivers a countershaft speed signal to the PCM. Countershaft speed sensor is located on the transaxle.

• Engine Coolant Temperature (ECT) Sensor — delivers input signal to PCM, indicating engine coolant temperature. ECT sensor is located in coolant pipe, near throttle body and contains a Red/White wire and Green/Blue wire in the harness connector.

• Engine RPM — determined by engine RPM signal delivered to PCM.

• Gear Position Sensor — sent to PCM by A/T gear position switch to indicate shift lever position. The A/T gear position switch is mounted on driver’s side of transaxle.

• Main shaft Speed Sensor —delivers a main shaft speed signal to the PCM. Main shaft speed sensor is located on the transaxle.

• Throttle Position (TP) Sensor — delivers input signal to PCM to indicate throttle position. TP sensor is mounted on throttle body.

• Vehicle Speed Sensor (VSS) — delivers input signal to PCM to indicate vehicle speed. Sensor is located on top of differential assembly.

Test Linear Solenoid to fix P1768

1.      With IGN off, disconnect the 4-pin shift control/linear solenoid valve harness connector.

2.      Using a DVOM meter, check the resistance between solenoid valve terminals No. 3 (Red wire) and No. 4 (White wire).  If resistance is about 5 ohms, go to next step. If resistance is not about 5 ohms, replace linear solenoid.

3.      Disconnect the PCM harness connector “E” (26-pin). Using DVOM check continuity between ground and PCM harness connector “E” terminal No. 16 (White wire), then terminal No. 3 (Red wire). If continuity does not exist, go to next step. If continuity exists, repair short in circuit between PCM harness connector “E” terminals No. 3 and 16, and linear solenoid.

4.      Reconnect the shift control/linear solenoid valve harness connector. Check resistance between PCM harness connector “E” terminals No. 3 and 16. If resistance is not about 5 ohms, go to next step. If resistance is about 5 ohms, repair loose terminal or open in circuit between PCM harness connector “E” terminals No. 3 and 16 and linear solenoid.

5.      Disconnect PCM harness connector “A” (26-pin) and connector “E” (26-pin). Turn ignition on. Check voltage between PCM harness connector “A” terminal No. 26 (Brown/Black wire) and connector “E” terminal No. 1 (Black/Yellow wire). If voltage is present, go to next step. If voltage is not present, check for open in circuit between PCM harness connector “E” terminal No. 1 and under hood fuse/relay box.

6.      Check for loose PCM connectors. Repair as necessary. If connectors are okay, substitute with a known good PCM and recheck system. If symptom or problem goes away, replace original PCM.

P1768 Acura

M5DA automatic transmission. Linear Solenoid

©, 2017 Rick Muscoplat

Posted on by Rick Muscoplat

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