Code 21: Throttle Position (TP) Sensor Circuit (Scan)
(1 of 2)
B
B
C
C
A
TP
A
CIRCUIT DESCRIPTION:
DIAGNOSTIC AIDS:
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 scan tool reads throttle position in voltage and
percentage of throttle blade opening. With ignition
ON or at idle, TP signal voltage should read between
.3 and .8 volt with the throttle closed, and increase at
a steady rate as throttle is moved toward 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.
If Code 23 is also set, check CKT 813 for faulty wiring
or connections. Check terminals at sensor for good
contact.
TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the
diagnostic chart.
An intermittent problem may be caused by a poor or
corroded connection, rubbed through wire connec-
tion, a wire that is broken inside the insulation, or a
corroded wire.
1.
With throttle closed the TP sensor should read
between.3and.8volt.Ifitdoesnot,checkthrottle
cable adjustment or for bent linkage.
Any circuitry that is suspected as causing the inter-
mittent complaint should be thoroughly checked for
backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, poor
terminal-to-wiring connections, corroded terminals
and/or wiring, or physical damage to the wiring har-
ness. After repairs, clear codes following “Clearing
Codes” in “ECM Self-Diagnostics.” Failure to do so
may result in codes not properly being cleared.
2.
3.
With the TP sensor disconnected, the TP voltage
should go low if the ECM and wiring are OK.
Probing CKT 813 with a DVOM to CKT 416
checks the sensor ground. A faulty sensor
ground will cause a Code 21.
Index
5C-102 - ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY)
90-823224--2 796
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1993, 1994, 1995, 1996, 1997 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
(4 votes, average: 4.5 out of 5)
Marine readers have rated 1993 1997 Mercury-MerCruiser GM V8 454 CID 7.4L and 502 CID 8.2L Marine Engines Service Manual Number 16 4.5 out of 5.0 based on 4 product reviews. Hugely helpful service manual! Perfect. Thank you!
Manuals are all Important for Technician
This book is invaluable if you do your own repairs. Great book.
Could not find a copy until a search brought me here.
Excellent print.
Thank you