SERVICE MANUAL NUMBER 23
TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
Code 33 (1 of 3): Manifold Absolute Pressure (MAP) Sensor Circuit (Non-Scan)
c
a
d
814
BLK
e
b
a - Manifold Absolute Pressure (Vacuum)
b - To ECT Sensor
c - To TP Sensor
d - Map Signal
e - Map And ECT Ground
CIRCUIT DESCRIPTION:
The Manifold Absolute Pressure (MAP) sensor responds to changes in manifold pressure
(vacuum). The ECM receives this information as a signal voltage that will vary from about
1-1.5
volts at closed throttle idle, to 4-4.8 volts at Wide Open Throttle (low vacuum).
If the MAP sensor fails, the ECM will substitute a fixed MAP value and use the engine rpm
to control fuel delivery.
DIAGNOSTIC AIDS:
An intermittent problem may be caused by a poor or corroded connection, rubbed through
wire connection, a wire that is broken inside the insulation, or a corroded wire.
Any circuitry that is suspected as causing the intermittent 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 harness. After repairs, clear codes following “Clearing
Codes” procedure at the front of this section. Failure to do so may result in codes not
properly being cleared. If Code 14 is also set, check for open ground CKT 814.
MAP Sensor
Altitude
Voltage Range
Feet
Meters
Below 1000
1000-2000
2000-3000
3000-4000
4000-5000
5000-6000
6000-7000
7000-8000
8000-9000
9000-10000
Below 305
305-610
3.8-5.5
3.6-5.3
3.5-6.1
3.3-5.0
3.2-4.8
3.0-4.6
2.9-4.5
2.8-4.3
2.6-4.2
2.5-4.0
610-914
914-1219
1219-1524
1524-1829
1829-2133
2133-2438
2438-2743
2743-3048
Index
90-861326--1
MARCH 1999
Page 5F-11
| 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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