6–20
Copyright © 1998 General Motors Corp.
W T E C I I E L E C T RO N I C C O N T RO L S T RO U B L E S H O OT I N G M A N UA L
Main code 13 indicates either a high or low input voltage. Low voltage is less than 8V. High voltage is over 35V.
Common causes for a low voltage code are:
•
Bad batteries
•
Faulty vehicle charging system
•
No battery-direct power and ground
Common causes for the high voltage code are:
•
Faulty vehicle alternator
•
Faulty vehicle voltage regulator
In the event of a power loss, the transmission fails to the ranges indicated in the following, depending upon which
latch valve releases first:
Active Indicator Clearing Procedure:
•
Power down
•
Manual
•
Self-clearing
Troubleshooting:
1. Connect the diagnostic tool and turn on vehicle ignition. Select Diagnostic Data to find input
voltage. Record reading.
2. Turn off vehicle ignition and remove the connectors from the ECU.
3. Check system voltage at wire 136A and 136C, pin B2 and B11. If power is low or high at this
point, and the diagnostic tool reading is also low or high, the vehicle wiring is suspect. Check for
fuse problems, lack of battery-direct power and ground, faulty charging system/batteries, and
loose or dirty connections (see Appendix A). Power may also be low or high at pins B2 and B11
(system power) if the batteries/charging system is faulty. Bad grounds may also cause incorrect
input power readings.
Attained Range
Fail to Range
Reverse and Neutral
Neutral
Low, 1
3C
2, 3, 4
4C usually, 3C sometimes
5
4C usually, 5C sometimes
6
5C
Main Code
Subcode
Meaning
13
12
Battery voltage to the ECU too low
13
13
Battery voltage to the ECU too low (medium)
13
23
Battery voltage to the ECU too high
CODE 13 XX — ECU INPUT VOLTAGE
(Figure 6–2)
