Mercury MerCruiser MIE 7.4L MPI User Manual

SERVICE MANUAL NUMBER 23
TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
90-861326--1 MARCH 1999 Page 5F-13
Code 33 (3 of 3): Manifold Absolute Pressure (MAP) Sensor Circuit (Non-Scan)
STEP ACTION VALUE YES NO
PROCEED TO
Is voltage reading over 4 volts? – Step 5 Step 8
5 1. Ignition OFF.
2. Connect a test light to battery positive
(B+).
3. Touch test light to harness terminal “B”
(MAP sensor signal).
Is test light on? – Step 6 Step 9
6 1. Disconnect ECM.
2. Touch test light connected to battery pos-
itive (B+) to harness terminal “B.” (See Note)
– Step 11 Step12
7
Connect DVOM from MAP sensor harness ter-
minal
“
C
”
to a good ground on engine.
–
Ste
p
14
Ste
p
13
7
minal
C
to
a
good
ground
on
engine
.
Is voltage reading over 4 volts?
–
Ste
14
Ste
13
8
Connect DVOM between harness terminal “B”
and engine ground (–).
Is voltage reading over 4 volts? – Step 10 Step 15
9 MAP sensor faulty. – – –
10 CKT 432 shorted to voltage. – – –
11 CKT 432 shorted shorted to ground. – – –
12 Faulty ECM. – – –
13
Faulty connection at ECM, CKT 416 open,
shorted to ground, or faulty ECM.
– – –
14
Faulty connection at ECM, CKT 814 open or
faulty ECM.
– – –
15
Open CKT 432, faulty connection at ECM or
faulty ECM.
– – –
16 Repair low or unsteady vacuum problem. – – –
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Index

Mercury MerCruiser MIE 7.4L MPI Specifications

General

Brand	Mercury
Model	MerCruiser MIE 7.4L MPI
Category	Engine
Language	English