Mercury MerCruiser MCM 454 Mag MPI Service Manual page 791

TROUBLE CODE DIAGNOSTICS - 7.4L MPI
Code 22 (2 of 3): Throttle Position (TP) Sensor Circuit (Scan) Low Signal
Voltage
TEST DESCRIPTION:
Number(s) below refer to step number(s) on the diagnostic table.
Step 2. With the throttle closed, the TP sensor voltage should read 0.3-0.9 volt. If it does
not, check the throttle cable adjustment or for bent or binding linkage.
Step 3. This test simulates a DTC 21. If the ECM recognizes the high signal voltage, the
ECM and wiring are OK.
Step 4. This test checks for the 5 volt reference on CKT 416.
STEP
1
2
3
4
5
Index
Page 5G-46
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ACTION
Was the "On-Board Diagnostic" (OBD) System
Check Performed?
1. Throttle closed.
2. Ignition "OFF."
Does scan tool indicate TP sensor voltage
less than the specified value?
1. Ignition "OFF."
2. Disconnect TP sensor harness connec-
tor.
3. Connect a jumper wire from harness ter-
minal "A" (CKT 416) to harness terminal "B"
(CKT 417).
4. Ignition "ON," engine "OFF."
Does scan tool indicate TP sensor voltage
greater than the specified value?
1. Ignition "OFF."
2. Connect DVOM from harness terminal
"A" (CKT 416) to a known good ground.
Does scan tool indicate TP sensor voltage
greater than the specified value?
Trouble code 22 is intermittent. Locate and
repair intermittent faulty connections. Refer to
"Diagnostic Aids".
SERVICE MANUAL NUMBER 23
VALUE YES NO
PROCEED TO
Go to
OBD
– Step 2
System
Check
.36 Volt Step 3 Step 5
4 Volts Step 8 Step 4
4 Volts Step 7 Step 6
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90-861326--1 MARCH 1999
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