TROUBLE CODE DIAGNOSTICS - 7.4L MPI
SERVICE MANUAL NUMBER 23
Page 5G-10
90-861326--1 MARCH 1999
Code 21 (1 of 2): Throttle Position (TP) Sensor Circuit (Non-Scan) Signal
Voltage High
STEP
ACTION
VALUE
YES
NO
PROCEED TO
1
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
–
Step 2
Go to
OBD
System
Check
2
1. Marine Diagnostic Code Tool switched to the
normal or “OFF” Mode.
2. Ignition “OFF.”
3. Disconnect throttle position sensor harness
connector.
4. Start engine and idle for 2 minutes or until
Marine Diagnostic Code Tool indicates a
stored trouble code.
5. Ignition “ON”, engine “OFF.”
6. Switch Marine Diagnostic Code Tool to “Ser-
vice Mode” and note the trouble code.
Is the trouble code 22 present?
–
Step 4
Step 3
3
1. TP sensor harness connector disconnected.
2. Ignition “ON,” engine “OFF.”
3. Connect DVOM from harness terminal “B”
(CKT 813) to harness terminal “A” (CKT 416).
(CKT 813) to harness terminal A (CKT 416).
Is voltage reading above specified value?
4 Volts
Step 6
Step 5
4
Locate and repair intermittent faulty connec-
tions. If OK, replace faulty TP sensor.
Is action
complete?
–
–
5
Locate and repair open in CKT 813. If a prob-
lem is found, repair as necessary.
Was a prob-
lem found?
–
Verify
Repair
Step 7
6
Locate and repair short to voltage in CKT 417.
If a problem is found, repair as necessary.
Was
a problem found?
–
Re air
Step 7
7
Repair faulty ECM connect
ion or replace faulty
ECM. Is action complete?
–
–
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