Mercury MerCruiser MCM 454 Mag MPI Service Manual page 705

TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
Code 21 (2 of 2): Throttle Position (TP) Sensor Circuit (Non-Scan)
STEP
1
2
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4
5 5
6 6
7
8
9
10
11
12
13
14
Index
Page 5F-8
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ACTION
Was the "On-Board Diagnostic" (OBD) System
Check Performed?
1. Ignition OFF.
2. Disconnect throttle position sensor har-
ness connector.
3. Ignition ON.
4. Connect DVOM from harness terminal
"A" (5 volt reference to harness terminal "B"
(sensor ground). ( d)
Is voltage reading over 4 volts?
Connect DVOM from harness terminal "A"
(CKT 416) to harness terminal "C" (throttle
position sensor signal, CKT 417). i i i l CKT 417)
Is voltage reading over 4 volts?
1. Ignition OFF.
2. Connect a test light to battery positive
(B+).
3. Touch test light to harness terminal "C"
(throttle osition sensor signal). (throttle position sensor signal)
Is test light on?
Connect DVOM between harness terminal "C"
and engine ground (–). and engine ground (–)
Is voltage over 4 volts?
Connect DVOM from throttle position sensor
harness terminal "A" to a good ground on
engine. i
Is voltage over 4 volts?
1. Disconnect ECM.
2. Touch test light to harness terminal "C"
(throttle position sensor signal) (throttle osition sensor signal).
Is test light on?
Check for CKT 417 shorted to voltage.
Open or CKT 417, faulty connection at ECM or
faulty ECM.
Throttle position sensor faulty.
Check for CKT 417 shorted to ground.
Faulty ECM.
Faulty connection at ECM, CKT 416, shorted
to ground or faulty ECM.
Faulty connection at ECM, CKT 813 open or
faulty ECM.
SERVICE MANUAL NUMBER 23
VALUE YES NO
PROCEED TO
Go to
OBD
– Step 2
System
Check
– – Step 3 Ste 3 Step 6 Ste 6
– – Ste 4 Step 4 Ste 5 Step 5
– – Step 7 Ste 7 Step 10 Ste 10
– – Ste 8 Step 8 Ste 9 Step 9
– – Step 14 Ste 14 Step 13 Ste 13
– – Step 11 Ste 11 Ste 12 Step 12
– –
– –
– –
– –
– –
– –
– –
90-861326--1 MARCH 1999
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