DTC P0778: Problem In A/T Clutch Pressure Control Solenoid Valve B Circuit

WARNING: This page is about a different car, the 2004 Honda Odyssey, 2003 Honda Odyssey, and 2002 Honda Odyssey. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Record all freeze data and review General Troubleshooting Information (see General Troubleshooting Information ) before you troubleshoot. This code is caused by an electrical circuit problem and cannot be caused by a mechanical problem in the transmission.

Disconnect the 2P connector from A/T clutch pressure control solenoid valve B.
Measure A/T clutch pressure control solenoid resistance at the solenoid valve connector.
Is the resistance 3-10 Ω?

YES - Go to step 3.

NO - Replace the A/T clutch pressure control solenoid valve B (see A/T Clutch Pressure Control Solenoid Valve A and B Replacement ).

Fig 1: Measuring A/T Clutch Pressure Control Solenoid Resistance At Solenoid Valve Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Disconnect PCM connector B (25P).
Check for continuity between PCM connector terminals B18 and body ground, and between B25 and body ground.
Is there continuity?

YES - Repair short ground in the wires between PCM connector terminals B18 and B25, and A/T clutch pressure control solenoid valve B.

NO - Go to step 5.

Fig 2: Checking Continuity Between PCM Connector Terminals B18 & Body Ground, And Between B25 & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Connect the A/T clutch pressure solenoid valve B connector.
Measure the resistance between PCM connector terminals B18 and B25.
Is the resistance 3-10 Ω?

YES - Go to step 7.

NO - Repair loose terminal or open in the wires between PCM connector terminals B18 and B25, and A/T clutch pressure control solenoid valve B.

Fig 3: Measuring Resistance Between PCM Connector Terminals B18 & B25
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Disconnect PCM connector D (16P).
Turn the ignition switch ON (II).
Measure the voltage between PCM connector terminals D5 and B20 or B22.
Is there battery voltage?

YES - Check for loose terminal fit in the PCM connectors. If necessary, substitute a known-good PCM and recheck.

NO - Check for blown No. 6 (15A) fuse in the driver's under-dash fuse/relay box. If the fuse is OK, repair open in the wire between PCM connector terminal D5 and the driver's under-dash fuse/relay box, between PCM connector terminals B20 and B22, and ground (G101), or repair poor ground (G101).

Fig 4: Measuring Voltage Between PCM Connector Terminals D5 & B20 Or B22
Courtesy of AMERICAN HONDA MOTOR CO., INC.