DTC 29

Code 27,28,29 Chart:

Code 27,28,29 Wiring Diagram:

CIRCUIT DESCRIPTION:


The gear switches are located inside the transaxle. They are pressure operated switches, normally closed. The ECM supplies 12 volts through each selected circuit to the switch. As road speed increases, hydraulic pressure applies the specific gear clutches and the gear switch opens. At this time, the ECM monitors a high, 12 volt potential, and interprets this to indicate that gear is applied. The ECM uses the gear signals to control fuel delivery (and TCC).

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to ECM CONNECTOR IDENTIFICATION under ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS for correct color code identification of circuit.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

Code 27 will set if:

^ No Code 29 present.

^ CKT 581 indicates ground or closed switch for 10 seconds when vehicle is in 4th gear operation.

^ CKT 581 indicates an open (drive) when the engine is first started.

^ CKT 446 is open when the engine is first started.

Code 28 will set if:

^ CKT 108 indicates ground or closed switch for 10 seconds when vehicle is in 4th gear operation.

^ CKT 108 indicates an open (drive) when the engine is first started.

^ CKT 446 is open when the engine is first started.

Code 29 will set if:

^ CKT 446 indicates ground or closed switch for 10 seconds when vehicle is in 4th gear operation, TCC locked, brake not applied.

^ CKT 446 is open when the engine is first started.

1. Must use a DVM. A test light will not light due to the very low current being supplied by the ECM.

2. Checks to see if CKT is grounded through the switch.

3. Checks for a good, properly operating switch and cheeks CKT within transaxle for an improper ground.

DIAGNOSTIC AIDS:


^ An intermittent may be caused by a poor connection, mis-routed harness, rubbed through wire insulation, or a wire broken inside the insulation. Check For:


^ Poor Connection at ECM pins. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

^ Mis-routed Harness Inspect wiring harness to insure that it is not too close to high voltage wires, such as spark plug leads.

^ Damaged Harness Inspect harness for damage. If harness appears OK, "Scan" while moving related connectors and wiring harness. A change in display would indicate the intermittent fault location.