Copyright © 1998 General Motors Corp. 6–75
WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL
Main code 43 indicates the ECU has detected an open solenoid low side driver (switch) or a low side (ground)
solenoid wire shorted-to-ground. An open or short prevents the ECU from turning off the F or K solenoid on the high
(power) and the low (ground) sides as required (described in Code 42 XX). A Code 43 XX can trigger a Code 45 XX.
NOTE: If solenoid resistance is about 1–2 Ohms, a short-to-ground code may not be set but could cause a
burned-out solenoid driver in the ECU. Replace the solenoid when this occurs (see appropriate
transmission Service Manual for replacement procedure). If the solenoid driver is burned out, 69 XX
codes will be set. See the troubleshooting procedure for 69 XX codes.
Active Indicator Clearing Procedure:
• Power down
• Manual
NOTE: Intermittent connections or lack of battery-direct power and ground connections may cause this and
other codes.
NOTE: Before troubleshooting, read Pages 6–17 and 6–18 of Section 6–5. Also, check battery and ECU input
voltages.
Troubleshooting:
1. Make sure the transmission connector is tightly connected. If the connector is properly connected,
disconnect the wiring harness at the transmission. Check the connector for water contamination
and check terminals for corrosion or damage. Clean or replace as necessary.
2. If the external harness-to-transmission connection is satisfactory, check the solenoid circuits at the
transmission connector for a short-to-chassis ground or a short-to-ground wire. (Tool J 38850 may
be useful in making this test.) If a short is found, drain the fluid, remove the control module (refer
to the Service Manual), isolate and repair the short. The short will probably be in the internal
wiring harness (refer to Figure 6–1 for solenoid location).
3. If the short is not found at the transmission connector, disconnect the connectors at the ECU and
check the wires of the solenoid circuit for shorts between the solenoid wires and all other terminals
in both connectors (at the ECU). If the short-to-ground is found in any of the wires, isolate and
repair the problem.
4. If the condition recurs, use spare wire(s) in the external harness for the solenoid circuit indicated
by the trouble code. See Appendix D for location of spare wire(s) and Appendix E for connector
assembly/disassembly information.
5. If the condition continues, examine the feedthrough connector. Replace if necessary (refer to
transmission Service Manual).
6. If the condition occurs again, replace the internal harness (refer to transmission Service Manual).
7. If the condition again recurs, replace the solenoid (refer to transmission Service Manual).
8. If the condition persists, replace the ECU. If replacing the ECU corrects the problem, reinstall the
original (bad) ECU to confirm that the problem is in the ECU. If the original ECU now works,
inspect the ECU connectors for any corrosion or damage which may cause an intermittent
condition. If the original problem recurs, reinstall the replacement ECU.
Main
Code
Subcode Meaning
43 21 Low Side Driver F Solenoid Circuit open
43 25 Low Side Driver K Solenoid Circuit open
43 26 Low Side Driver N Solenoid Circuit open
CODE 43 XX — SOLENOID LOW SIDE CIRCUIT, OPEN DRIVER, OR
WIRE SHORTED-TO-GROUND (Figures 6–27, 6–28)
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