Download DTC P1351 Ignition Coil Control Circuit High Voltage

Document ID: 34079
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1996 Chevrolet Chevy K Pickup - 4WD
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Chevy Pickup, GMC Pickup, Suburban, Tahoe, Yukon (VIN C/K) Service Manual
|
Document ID: 34079
DTC P1351 Ignition Coil Control Circuit High Voltage
Circuit Description
The enhanced ignition system uses the crank sensor in order to provide the timing input to the
VCM. The VCM uses this reference pulse in order to determine the individual ignition spark timing
for each cylinder.
Once the VCM calculates the ignition timing, the ignition coil module on the IC circuit receives the
timing signal. Each timing pulse received by the ignition coil module on the IC circuit triggers the
coil module in order to operate the ignition coil. The secondary ignition voltage is induced, and then
the secondary ignition voltage is sent to the distributor for distribution to each spark plug. This DTC
is a type A DTC.
The IC signal voltage ranges from about 0.5 volt to 4.5 volts.
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Conditions for Setting the DTC
The voltage on the ignition control circuit exceeds 4.9 volts, and the engine speed is less than
250 RPM.
Action Taken When The DTC Sets
• The VCM turns the MIL ON when this DTC is reported and one failure has occurred.
• The VCM records the operating conditions at the time the Diagnostic Fails. Freeze Frame and
Failure Records store this information.
Conditions for Clearing the MIL/DTC
The VCM turns OFF the MIL after 3 consecutive driving trips without a fault condition present. A
history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (the coolant
temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant
temperature exceeds 71°C (160°F) during that same ignition cycle) or the scan tool clearing
feature has been used.
Diagnostic Aids
A poor connection, a rubbed through wire in the insulation, or a wire broken inside the insulation
will cause an intermittent.
Check for the following conditions:
• Poor connection
• Damaged harness: Inspect the VCM harness connectors for the following conditions:
- Backed out terminal C3 pin 9
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- A poor terminal to wire connection and
- Damage to the harness.
• Intermittent test - If the connections and the harness check OK, monitor a digital voltmeter
connected between VCM connector C3 pin 9 and C4 pin 18 while moving related connectors
and wiring harness. If the failure is induced, the voltage reading will change. This may help
to isolate the location of the malfunction.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
2. This determines if the DTC is an intermittent.
3. This check determines if the IC signal from the VCM is available at the ignition coil driver.
4. The remaining tests begin to check that the coil driver circuitry is OK.
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Step
Action
Value
(s)
1
Important: Before clearing DTCs, use the scan
tool in order to record the freeze frame and the
failure records for reference because the Clear
Info function will lose the data.
--
Was the Powertrain On-Board Diagnostic (OBD)
System Check performed?
2
1. Clear the DTCs.
2. Disconnect the injector connector.
3. Crank the engine for 30 seconds.
1. Turn OFF the ignition.
2. Disconnect the VCM gray harness
connector.
3. Check the resistance between the VCM
Ignition Control and the ignition coil
module connector terminal B.
Go to Step 3
Go to Diagnostic
Aids
Go to Step 9
Go to Step 4
Go to Step 6
Go to Step 5
Go to Step
16
--
Go to Step 7
Go to Step 8
Go to Step
16
--
10 Ω
Is the resistance less than the specified value?
5
Go to Powertrain
On Board
Diagnostic
(OBD) System
Go to Step 2
Check
1. Turn OFF the ignition.
2. Reconnect the injector connector.
3. Disconnect the ignition coil module
connector.
4. Probe the ignition coil module connector
terminal B with a voltmeter to ground.
5. With the voltmeter on the AC scale, crank 1-4 V
the engine.
6. Monitor the voltage reading.
Is the voltage reading within the specified
value?
4
No
--
Does DTC P1351 set?
3
Yes
Repair the open IC circuit between the VCM
and the ignition coil module. Refer to Wiring
Repairs in Engine Electrical.
--
Is the action complete?
Check for a faulty VCM connection.
6
-Was a problem found?
7
Repair the faulty VCM connection. Refer to
Wiring Repairs in Engine Electrical.
--
Is the action complete?
Replace the VCM.
8
Important: If the VCM is faulty, reprogram the
VCM. Refer to VCM
Replacement/Programming .
--
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Is the replacement complete?
9
1. Turn OFF the ignition.
2. Connect a test lamp to B+.
3. Probe the ignition coil module harness
connector terminal C.
10
11
12
13
--
Was a problem found?
14
Replace the ignition coil module. Refer to
Ignition Coil Driver Module.
--
Is the action complete?
15
Repair the ignition coil module connection.
Refer to Wiring Repairs in Engine Electrical.
--
Is the action complete?
16
1. Using the scan tool, select the DTC and
the Clear Info.
2. Start the Engine.
3. Idle at the normal operating temperature.
4. Select the DTC and the Specific.
5. Enter the DTC number which was set.
6. Operate the vehicle within the conditions
for setting this DTC as specified in the
supporting text.
Does the scan tool indicate that this diagnostic
ran and passed?
Go to Step
16
--
Go to Step
13
Go to Step 12
Go to Step
16
--
Go to Step
15
Go to Step 14
Go to Step
16
--
Go to Step
16
--
Go to Step
17
Go to Step 2
--
Is the repair complete?
Check for a faulty ignition coil module
connection.
Go to Step 10
--
Is the test lamp on both terminals?
Repair the faulty ignition coil module feed
circuit. Refer to Wiring Repairs in Engine
Electrical.
Go to Step
11
--
Is the repair complete?
1. Turn ON the ignition.
2. Connect a test lamp to a ground.
3. Probe the ignition coil module harness
connector terminals D and A.
--
--
Is the test lamp on?
Repair the open ignition coil module ground
circuit. Refer to Wiring Repairs in Engine
Electrical.
Go to Step
16
--
Using the scan tool, select the Capture Info and
the Review Info.
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17
Are any DTCs displayed that have not been
diagnosed?
Page 5 of 5
--
Go to The
Applicable
DTC Table
System OK
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