MIL ON - Intermittent DTC 21 Set
88isuzu02BULLETIN NUMBER SB88-03-001
ISSUE DATE March 8, 1988
GROUP EMISSIONS
CALIF. P'UP (KB) AND TROOPER II (KT) ERRONEOUS TROUBLE CODE 21 (4ZD1 ENGINE)
VEHICLES AFFECTED
1985-1987 P'UP (KB) and Trooper II (KT) California models with 4ZD1 engine.
SERVICE INFORMATION
When the engine is cold, the "Check Engine" light may flash when traveling in third gear with engine speed between 3500 and 3900 rpm. It will go off when the throttle is released or the transmission is shifted. System check of the vehicle indicates Trouble Code
21 (idle switch circuit open or WOT switch circuit shorted), but diagnosis reveals that these problems do not exist.
To eliminate the "Check Engine" light coming on under these conditions, follow the procedure in this Service Bulletin for rerouting the vacuum hoses.
FIGURE 1:
SERVICE PROCEDURE
Refer to Figure 1 for locations of vacuum hoses referenced as (a) through (f).
1. Disconnect vacuum hose (a) between the idle switch and the tee fitting. Discard this hose.
2. Disconnect vacuum hose (b) from canister. Remove tee fitting.
3. Connect vacuum hose (c) to the canister.
4. Remove and discard clip holding hoses (d) and (f) together.
5. Disconnect vacuum hose (f) from carburetor.
6. Connect new vacuum hose (e) to idle switch at one end and to tee fitting (removed in Step 2) at other end.
7. Connect vacuum hose (b) to carburetor at one end and to tee fitting at other end.
8. Connect vacuum hose (f) to tee fitting.
9. Place new hose routing label over the existing label.
PARTS INFORMATION
FLAT RATE MANUAL INFORMATION