TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
SERVICE MANUAL NUMBER 23
Code 21 (2 of 3): Throttle Position (TP) Sensor Circuit (Scan)
TEST DESCRIPTION:
Number(s) below refer to step number(s) on the diagnostic table.
Step 2: With throttle closed the TP sensor should read between .3 and .8 volt. If it does not,
check throttle cable adjustment or for bent linkage.
Step 4: With the TP sensor disconnected, the TP voltage should go low if the ECM and wir-
ing are OK.
Step 7: Probing CKT 813 with a DVOM to CKT 416 checks the sensor ground. A faulty sen-
sor ground will cause a Code 21.
STEP
ACTION
VALUE
YES
NO
PROCEED TO
Go to
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
OBD
System
1
–
Step 2
Check
1.
2.
Throttle closed.
Ignition ON.
Does scan tool indicate throttle position
sensor voltage greater than 4 volts?
2
3
Step 5
Step 4
–
Step 3
Step 3
–
Does scan tool indicate throttle position
sensor voltage less than .36 volts?
Code 21 is intermittent, refer to “Diagnostic
Aids” on facing page.
–
1.
Ignition OFF.
2.
connector. Jumper throttle position sensor har-
ness terminals “A” and “C” together.
Disconnect throttle position sensor electrical
4
3.
Ignition ON.
4.
Scan tool should indicate throttle position
sensor voltage greater than 4 volts.
Does it?
–
Step 11 Step 6
1.
2.
Ignition OFF.
Disconnect throttle position sensor connec-
tor.
5
6
3.
Ignition ON.
Does scan tool indicate voltage over 4
volts?
–
–
Step 8
Step 7
1.
Ignition OFF.
. Connect DVOM between throttle position
sensor harness terminal “A” and ground.
Ignition ON.
Is voltage over 4 volts?
2
3.
Step 9 Step 10
Index
Page 5F-24
90-861326--1 MARCH 1999
| 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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