SERVICE MANUAL NUMBER 23
TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
Code 33 (2 of 3): Manifold Absolute Pressure (MAP) Sensor Circuit (Scan)
TEST DESCRIPTION:
Number(s) below refer to step number(s) on the diagnostic table.
Step 4. Engine misfire or a low, unstable idle may set Code 33. Disconnect MAP sensor and
system will go into backup mode. If the misfire or idle condition remains, refer to “Trouble-
shooting.”
Step 5. If the ECM recognizes the low MAP signal, the ECM and wiring are OK.
NOTE: If engine is idling rough, unstable or incorrect, this condition must be corrected be-
fore proceeding (refer to troubleshooting section).
STEP
ACTION
VALUE
YES
NO
PROCEED TO
Go to
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
OBD
System
Check
1
2
–
Step 2
Engine idling
Does scan tool display a MAP sensor volt-
age of less than 1 volt?
–
–
Step 4
Step 5
Step 3
Step 3
Does scan tool display a MAP sensor volt-
age of greater than 4 volts?
Code 33 is intermittent, if not additional codes
were stored, refer to “Diagnostic Aids” on fac-
ing page.
3
4
–
–
–
1. Ignition OFF.
2.
Disconnect MAP sensor electrical con-
nector.
3.
Jumper MAP sensor harness terminals
“B” and “C” together.
4.
Start engine.
Does scan tool display a MAP sensor volt-
age of greater than 4 volts?
–
Step 9
Step 7
Step 6
Step 8
5
6
1. Ignition OFF.
2.
Disconnect MAP sensor electrical con-
nector.
3.
Start engine.
Does scan tool display a MAP sensor volt-
age of less than 1 volt?
–
–
1. Ignition OFF.
2.
Connect DVOM between MAP sensor
harness terminal “C” and “A.”
3.
Ignition ON.
Is voltage over 4 volts?
Step 11 Step 10
Index
90-861326--1
MARCH 1999
Page 5F-29
| 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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