On Board Diagnostic System — Code No. 28 (EGR Solenoid Valve — Vacuum) / Code No. 29 (EGR Solenoid Valve — Vent)
F2-89flowchartCode No. 28 (EGR Solenoid Valve — Vacuum)
1
STEP 1: Disconnect connector from ECM; is there battery positive voltage at ECM terminal 3O with ignition switch ON?
Yes
Does ECM terminal connector have a poor connection? If not, replace ECM (see page F2-141); if it does, repair or replace the connector
No
2
STEP 2: In same condition as step 1, is there battery positive voltage at EGR solenoid valve (vacuum) connector terminal?
Yes
Repair or replace wire
No
3
STEP 3: Is EGR solenoid valve (vacuum) OK? (see page F2-126)
No
Replace EGR solenoid valve (vacuum)
Yes
Look for a short or open circuit in wiring from main relay (FUEL INJ relay) to solenoid valve
Code No. 29 (EGR Solenoid Valve — Vent)
1
STEP 1: Disconnect connector from ECM; is there battery positive voltage at ECM terminal 3P with ignition switch ON?
Yes
Does ECM terminal have a poor connection? If not, replace ECM (see page F2-141); if it does, repair or replace the connector
No
2
STEP 2: In same condition as step 1, is there battery positive voltage at EGR solenoid valve (vent) connector terminal wire?
Yes
Repair or replace wire
No
3
STEP 3: Is EGR solenoid valve (vent) OK? (see page F2-126)
No
Replace EGR solenoid valve (vent)
Yes
Look for a short or open circuit in wiring from main relay (FUEL INJ relay) to solenoid valve