Diagnosis - EEC/MX1: Other Geo Metro I

TCU

The TCU receives information from various input devices and uses this information to control both solenoids on transmission valve body for transmission shifting.

The TCU contains a self-diagnostic system, which will store trouble code if failure or problem exists in electronic control system. Trouble code can be retrieved to determine problem area. See SELF-DIAGNOSTIC SYSTEM .

Park/Neutral Position (PNP) Switch Signal

PNP switch delivers an input signal to ECT ECU indicating shift lever position. Switch is located on side of transmission.

Throttle Position Sensor (TPS) Signal

TPS delivers an closed throttle and variable throttle position input signals to ECT ECU. TPS is located on side of throttle body. (Scheme 15)

Vehicle Speed Sensor (VSS) Signal

Vehicle speed signal is delivered to ECT ECU by No. 1 and No. 2 speed sensors. (Scheme 16)

Direct Clutch Solenoid

The TCU controls transmission shifting by delivering an output signal to operate solenoid. Solenoid is located on transmission valve body. see scheme 1 Direct clutch solenoid controls delivery of line pressure to 2-3 shift valve.

2nd Brake Solenoid

The TCU controls transmission shifting by delivering an output signal to operate solenoid. Solenoid is located on transmission valve body. see scheme 1 2nd brake solenoid controls delivery of line pressure to 1-2 shift valve.

Scheme 15

Scheme 16

CODE 21: DIRECT CLUTCH SOLENOID OPEN CIRCUIT

1. Perform TCU DIAGNOSTIC CIRCUIT CHECK. Ensure ignition is on and shift selector is in "D" position. Disconnect solenoid harness connector. see scheme 6 Using DVOM, measure voltage between solenoid harness connector terminal No. 2 ( Orange wire) and ground. If battery voltage is present, go to step 3).
2. If battery voltage is not present, measure voltage between TCU terminal No. 4 (14-pin connector) and ground. see scheme 8 DO NOT disconnect connector. If battery voltage is present, inspect and repair circuit between TCU and solenoid harness connector. If battery voltage is not present, check for poor TCU harness connection. Repair as needed. If connection is okay, replace TCU and retest.
3. Using ohmmeter, measure resistance between solenoid component connector terminal No. 2 ( Red wire) and ground. If 10-15 ohms is present, inspect and repair solenoid harness connection. If connection is okay, replace TCU and retest.
4. If 10-15 ohms is not present, move shift selector to "P" position. Raise and support vehicle. Remove oil pan and drain fluid. Disconnect direct solenoid harness connector. Check continuity of circuit between solenoid and harness connector. Repair as needed. If circuit is okay, replace solenoid and retest.

CODE 22: DIRECT CLUTCH SOLENOID SHORTED CIRCUIT

1. Perform «TCU DIAGNOSTIC CIRCUIT CHECK»(ref-56876-S34291223762001011700000). Ensure ignition is turned to "LOCK" position. Disconnect TCU 14-pin connector. see scheme 8 Using ohmmeter, measure resistance between TCU terminal No. 4 and ground. If 10-15 ohms is present, replace TCU and retest.
2. If 10-15 ohms is not present, disconnect solenoid harness connector. Resistance should increase to infinite measurement. If resistance is not within specification, inspect and repair short to ground.
3. If resistance is infinite, raise and support vehicle. Remove oil pan and drain fluid. Disconnect direct clutch solenoid harness connector. Check continuity of circuit between solenoid and harness connector, and ground. Continuity should not exist. Repair as needed. If circuit is okay, replace solenoid and retest.

CODE 23: 2ND BRAKE SOLENOID OPEN CIRCUIT

1. Perform «TCU DIAGNOSTIC CIRCUIT CHECK»(ref-56876-S34291223762001011700000). Ensure ignition is on and shift selector is in "D" position. Disconnect solenoid harness connector. see scheme 6 Using DVOM, measure voltage between solenoid harness connector terminal No. 1 ( Orange / Green wire) and ground. If battery voltage is present, go to step 3).
2. If battery voltage is not present, measure voltage between TCU terminal No. 6 (14-pin connector) and ground. see scheme 8 DO NOT disconnect connector. If battery voltage is present, inspect and repair circuit between TCU and solenoid harness connector. If battery voltage is not present, check for poor TCU harness connection. Repair as needed. If connection is okay, replace TCU and retest.
3. Using ohmmeter, measure resistance between solenoid component connector terminal No. 1 ( Yellow wire) and ground. If 10-15 ohms is present, inspect and repair solenoid harness connection. If connection is okay, replace TCU and retest.
4. If 10-15 ohms is not present, move shift selector to "P" position. Raise and support vehicle. Remove oil pan and drain fluid. Disconnect 2nd brake solenoid harness connector. Check continuity of circuit between solenoid and harness connector. Repair as needed. If circuit is okay, replace solenoid and retest.

CODE 24: 2ND BRAKE SOLENOID SHORTED CIRCUIT

1. Perform «TCU DIAGNOSTIC CIRCUIT CHECK»(ref-56876-S34291223762001011700000). Ensure ignition is turned to LOCK position. Disconnect TCU 14-pin connector. see scheme 8 Using ohmmeter, measure resistance between terminal No. 6 and ground. If 10-15 ohms is present, replace TCU and retest.
2. If 10-15 ohms is not present, disconnect solenoid harness connector. Resistance should increase to infinite measurement. If resistance is not within specification, inspect and repair short to ground.
3. If resistance is infinite, raise and support vehicle. Remove oil pan and drain fluid. Disconnect 2nd brake solenoid harness connector. Check continuity of circuit between solenoid and harness connector, and ground. Continuity should not exist. Repair as needed. If circuit is okay, replace solenoid and retest.

CODE 25: RD2L SHORTED SIGNAL

1. Preform TCU DIAGNOSTIC CIRCUIT CHECK. Ensure ignition is turned to LOCK position. Disconnect TCU 14-pin connector. see scheme 8 Turn ignition on. Move shift selector from "P" to "D", then back to "P". Monitor test light or voltmeter connected to monitor connector. If code 25 remains, go to next step. If code 25 is no longer displayed, replace Engine Control Module (ECM) and retest. see scheme 7
2. Turn ignition to LOCK position. Using ohmmeter, measure resistance between TCU terminal No. 5 (14-pin connector) and ground. Infinite resistance should be present. If resistance is within specification, replace TCU and retest. If resistance is not within specification, repair short to ground in circuit and retest. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-56876-S10316955122001011700000).

CODE 31: VEHICLE SPEED SENSOR (VSS) INPUT

1. Preform «TCU DIAGNOSTIC CIRCUIT CHECK»(ref-56876-S34291223762001011700000). Raise and support front of vehicle. Start and operate vehicle in drive ("D") at idle. Backprobing TCU 14-pin connector, measure voltage between terminals No. 11 and 12. see scheme 7and see scheme 8.
2. If a 0-3 volt pulse is measured, code may be set by intermittent problem. Inspect all connections. Repair as needed. If no pulse is present, disconnect harness connector at VSS. Measure voltage between component terminals. If 0-3 volt pulse is not present, replace VSS.
3. If 0-3 volt pulse is present, turn ignition off. Using ohmmeter, check continuity of both circuits between component and TCU. Also check for continuity to ground. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-56876-S10316955122001011700000). Repair circuit(s) if an open or short exists. Retest after all repairs are completed.

CODE 32: PARK/NEUTRAL POSITION (PNP) SWITCH SIGNAL

Note. Code is set if TCU does not receive any signal from PNP or receives 2 or more signals simultaneously.

1. Turn ignition on. Disconnect PNP harness connector. Using DVOM, measure voltage between harness connector terminal No. 7 and ground, and terminal No. 8 and ground. If battery voltage is not present, inspect No. 16 (BACK) fuse under dash. Replace as needed.
2. If fuse is okay, inspect and repair power supply circuits between PNP switch and fuse. Refer to the appropriate wiring diagram in «WIRING DIAGRAMS»(ref-56876-S10316955122001011700000).
3. Turn ignition off. Disconnect TCU harness connector. see scheme 7 Inspect continuity of each circuit between TCU and PNP switch. see scheme 8and (Scheme 17). Repair as needed. Ensure there is no short to ground in any circuit tested. If PNP switch is suspected, see «PARK/NEUTRAL POSITION (PNP) SWITCH»(ref-56876-S34206141872001011700000) under COMPONENT TESTING.

Scheme 17

CODE 33: ENGINE SPEED INPUT

1 Perform TCU DIAGNOSTIC CIRCUIT CHECK. Ensure ignition is turned to LOCK position. Disconnect noise suppressor filter connector. (Scheme 18) Connect jumper wire between filter harness connector terminal No. 2 (MD6Brown wire) and No. 3 (MD6Brown/White wire).

2) Retrieve trouble codes. If code 33 is not displayed, replace noise suppressor. If code 33 is displayed, turn ignition to LOCK position. Remove jumper wire. Disconnect ignition coil connector.

3) Using ohmmeter, check continuity between ignition coil harness connector terminal No. 2 (MD6Brown/White wire) and noise suppressor harness connector terminal No. 3 (MD6Brown/White wire). If continuity does not exist, inspect and repair circuit as needed.

4) If continuity does exist, disconnect TCU 10-pin harness connector. Check continuity between noise suppressor harness connector terminal No. 2 (MD6Brown wire) and TCU harness connector terminal No. 4. see scheme 8

5) If continuity does not exist, inspect and repair circuit as needed. If continuity does exist, replace TCU and retest.

Scheme 18

THROTTLE POSITION SENSOR CIRCUIT CHECK

1. Ensure ignition is off. Disconnect TCU harness connectors. see scheme 7 Turn ignition on. Using DVOM, measure voltage between terminals No. 3 and 7 of 14-pin connector. see scheme 8
2. While monitoring voltage, slowly depress accelerator pedal to wide open throttle (WOT). Voltage should increase from 0-12 volts. If voltage is not within specification, go to step 5). If voltage is within specification, go to next step.
3. Measure voltage between terminals No. 3 and 8 of 14-pin connector. see scheme 8 While monitoring voltage, slowly depress accelerator pedal to wide open throttle (WOT). Voltage should increase from 0-12 volts, then decrease from 12-0 volts. If voltage is not within specification, go to step 5). If voltage is within specification, go to next step.
4. Measure voltage between terminals No. 3 and 9 of 14-pin connector. see scheme 8 While monitoring voltage, slowly depress accelerator pedal to wide open throttle (WOT). Voltage should pulse twice from 0-12 volts, then decrease from 12-0 volts. If voltage is not within specification, go to next step. If voltage is within specification, system is okay.
5. Inspect TCU and TPS harness connections. Using ohmmeter, check all circuits for continuity and short to ground. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-56876-S10316955122001011700000). If all circuits are okay, see appropriate repair manual for further TPS diagnostic procedures.

PARK/NEUTRAL POSITION (PNP) SWITCH

Ensure ignition is off. Disconnect PNP switch harness connector. Check continuity of specified circuits. Refer to the PARK/NEUTRAL POSITION (PNP) SWITCH CONTINUITY table. Make sure there is no continuity to ground or continuity to any other terminals. Refer to the appropriate wiring diagram in WIRING DIAGRAMS. Also refer to Figs. see scheme 7 and see scheme 8. Replace switch as needed.

PARK/NEUTRAL POSITION (PNP) SWITCH CONTINUITY