This page is designed to help provide some basics for checking codes and identifying what they mean on an ISUZU Trooper.
Note: not all models are equipped with the self-diagnosis feature. If the instrument cluster has a "Check Engine" light then it's equipped, if it does not then it's not equipped.
On models equipped with the self-diagnosis, when an issue is detected, the "Check Engine" light comes on and the ECM (Electronic Control Module) stores a trouble code into memory. Codes will be stored in memory until the battery voltage to the ECM is interrupted for 30 seconds or more.
Locating the Diagnostic Wires
On 1985 Troopers, the diagnostic wires are located under the dashboard console near the radio on the passenger's side. (Source: Haynes Repair Guide)
On 1986 through 1987 Troopers, the diagnostic wires are located under the dashboard near the cigarette lighter on the driver's side. (Source: Haynes Repair Guide)
On 1988 and later Troopers, the diagnostic wires are located under the center console, typically accessible by removing the change tray (photo from a 1991 2.8L V6 Trooper):
Once the diagnostic wires have been located, simply connect these two wires then turn the ignition to "On", do NOT start the engine (photo from a 1991 2.8L V6 Trooper):
The Check Engine Light will flash in two sets (flash or flashes, brief pause, flash or flashes) representing the first and second digit of the code (photo from a 1991 2.8L V6 Trooper):
Initially you should see a "code 12" flash three times in a row (one flash, brief pause, two flashes) which is a normal diagnostic code which simply means the system is operating.
If there are codes in the ECM system, each code will be flashed three times, then "code 12" will be flashed again indicating the display of stored trouble codes has been completed.
If there are no codes in the ECM system, "code 12" will continue to flash until the diagnostic wires are disconnected.
What the Codes Mean
Both the Haynes and Chilton repair guides include a list of trouble codes, the following are other sites online that can be used to determine what a code means: