SERVICE MANUAL NUMBER 23
TROUBLE CODE DIAGNOSTICS - 7.4L MPI
Code 22 (1 of 3): Throttle Position (TP) Sensor Circuit (Scan) Low Signal
Voltage
c
b
e
B
i
B
a
C
f
C
A
h
A
g
d
a - Throttle Position Sensor
b - Front View Of Connector
c - To IAT Sensor
d - To Map Sensor
e - Sensor Ground
f - TP Signal
g - 5V Reference
h - Wide Open Throttle
i - Idle
CIRCUIT DESCRIPTION:
The Throttle Position (TP) Sensor provides a voltage signal that changes as throttle blades
open or close. Signal voltage should vary from about .7 volts at idle to about 4.5 volts at Wide
Open Throttle (W.O.T.).
The TP signal is one of the most important inputs used by the Electronic Control Module
(ECM) for fuel control and for most of the ECM controlled outputs.
The ECM supplies a 5 volt signal to the sensor through CKT 416. CKT 813 is the TP sensor
ground circuit. The TP sensor will send a voltage signal back to the ECM, through CKT 417,
according to where the throttle blades are positioned.
DIAGNOSTIC AIDS:
Check for the following conditions:
•
Poor connection at ECM. Inspect harness connectors for backed out terminals,
improper mating, broken locks, improperly formed or damaged terminals, and poor ter-
minal to wire connection.
•
Damaged harness. Inspect the wiring harness for damage. If the harness appears to be
OK, observe the TP sensor display on the scan tool while moving connectors and wiring
harnesses related to the TP sensor. A change in the TP sensor display will indicate the
location of the fault.
•
•
The scan tool reads throttle position in voltage and percentage relative to the throttle
blade opening With ignition “ON”, engine “OFF”, throttle blades closed (idle), the voltage
should be 0.3-0.9 volts The voltage should steadily increase as the throttle is moved
toward Wide Open Throttle (WOT).
If DTC 34 is also set, check for a short to ground in CKT 416 or CKT 416E.
After repairs, clear DTC’s following “Clearing Trouble Codes” procedure at the front of this
section. Failure to do so may result in DTC’s not properly being cleared.
90-861326--1
MARCH 1999
Page 5G-45
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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