Power Mode Mismatch
Power Mode Mismatch |
Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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DTC Descriptors |
DTC B1370 01
Device Ignition 1 (ON and START) Circuit Short to Battery
DTC B1370 06
Device Ignition 1 (ON and START) Circuit Short to Ground or Open
DTC B1380 01
Device Ignition ACCESSORY Circuit Short to Battery
DTC B1380 06
Device Ignition ACCESSORY Circuit Short to Ground or Open
DTC B1440 00
Power Mode Master Input Circuits Mismatch
DTC B1441 01
Device Ignition OFF, RUN, and CRANK Circuit Short to Battery
DTC B1441 06
Device Ignition OFF, RUN, and CRANK Circuit Short to Ground or Open
Diagnostic Fault Information |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance | ||||||||||||||||||
B+ - Terminal 1 | B1370 06, B1380 06, B1440 00, U0100-U0299, 1, 5, 6 | B1370 06, B1380 06, B1440 00, U0100-U0299, 1 | - | - | ||||||||||||||||||
Ignition - Terminal 2 | B1370 06, B1380 06, B1440 00, U0100-U0299, 1, 5, 6 | B1370 00, 1 | B1370 01, B1440 00, U0100-U0299, 1, 6 | - | ||||||||||||||||||
Ignition- Terminal 3 | 1 | 1 | 1 | - | ||||||||||||||||||
Ignition - Terminal 4 | B1370 06, B1380 06, B1440 00, U0100-U0299, 1, 5, 6 | B1380 06, 1 | B1380 01, P1629, 1 | - | ||||||||||||||||||
Ignition - Terminal 5 | B1370 06, B1380 06, B1440 00, U0100-U0299, 1, 5, 6 | B1440 00, B1441 06, 1 | B1440 00, B1441 01, 1 | - | ||||||||||||||||||
Ignition Voltage - BCM Terminal 21 X4 | B1428 00, 4 | 2 | 3 | - | ||||||||||||||||||
Accessory Wakeup Serial Data, BCM Terminal 19 X4 | U1814, 4 | U0100-U0299, P0513 00 | - | - | ||||||||||||||||||
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Circuit/System Description |
The vehicle power mode master (PMM) is the body control module (BCM). The ignition switch is a low current switch with multiple discrete circuits to the BCM. The BCM logic uses the ignition switch positions to identify the operator's desired power mode and activate specific discrete signals, and serial data messages for the operation of different subsystems as necessary. Other modules which have switched voltage inputs may operate in a default mode if the PMM serial data message does not match what the individual module can detect from its own connections.
The PMM will activate relays and other direct outputs of the PMM as needed according to the calculated power mode. Some relays controlled by the BCM are switched ignition voltage outputs that are pass through circuits within the BCM directly from the ignition switch. If these circuits short to ground, the B+ circuit fuse to the ignition switch will open.
Conditions for Running the DTC |
B1370 01, B1380 01
Ignition switch is in the RUN or CRANK positions.B1370 06, B1380 06
Ignition switch is in the RUN or ACCESSORY positions.B1440 00
Ignition switch is in the RUN position.B1441 01, B1441 06
Ignition switch is in the CRANK position.Conditions for Setting the DTC |
B1370 01
Ignition circuit is shorted to voltage.B1370 06
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Ignition circuit is open.
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Ignition circuit shorted to ground.
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B+ circuit of the ignition switch is open or shorted to ground.
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Ignition relay control circuit open, including relay coil and ground.
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B1380 01
Accessory circuit is shorted to voltage.B1380 06
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Accessory circuit is open.
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Ignition or accessory circuit shorted to ground.
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B+ circuit of the ignition switch is open or shorted to ground.
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B1440 00
BCM detects an open or short to voltage on the off/run/crank signal circuit when both ignition ACCESSORY/RUN and ignition RUN/CRANK parameters are active.BCM detects an open on the B+ circuit to the ignition switch while the engine is running.
B1441 01
Off/run/crank signal circuit is shorted to voltage.B1441 06
Off/run/crank signal circuit is open.Actions Taken When the DTC Sets |
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The BCM operates in a fail-safe power mode dependent on the last valid power mode detected and the state of the engine run flag data on the serial data communications circuits.
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The other modules on the vehicle operate in a fail-safe power mode dependent on the last valid power mode transmitted by the BCM and the state of the engine run flag on the serial data communications circuits.
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Conditions for Clearing the DTC |
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The condition responsible for setting the DTC no longer exists.
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A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.
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Diagnostic Aids |
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A short to ground in the accessory wake up serial data circuit will cause an open fuse to the ignition switch. DTC U1814 should be current.
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A short to ground in the run/crank ignition 1 voltage circuit of the run crank relay will cause an open fuse to the ignition switch. DTC B1428 should be current.
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The power modes and controls are determined using BCM logic. Comparing the BCM Power Mode data display parameters listed in Circuit/System Verification will determine if there is a power mode fault.
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Reference Information |
Schematic Reference
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Power Moding Schematics
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Power Distribution Schematics
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Connector End View Reference
Component Connector End Views
Description and Operation
Retained Accessory Power Description and Operation
Electrical Information Reference
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification |
1. |
Verify that DTC U1814 or B1428 is not set.
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2. |
If any of the DTCs are set, refer to
Diagnostic Trouble Code (DTC) List - Vehicle
for diagnosis.
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3. |
With a scan tool, verify the Power Mode data display parameters match the chart below. The PMM Power Mode Parameters table below illustrates the correct state of these input parameters (circuits) in correspondence to the ignition switch position. The circuits which the individual parameters are related to are in parentheses.
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PMM Power Mode Parameters
Ignition Switch Position | Current Power Mode | Ignition Off/Run/Crank (Ignition Switch, Terminal 5) | Ignition Accessory/Run (Ignition Switch, Terminal 4) | Ignition Run/Crank (Ignition Switch, Terminal 2) |
Off Key Out | Off | Key Out/ACC | Inactive | Inactive |
Off Key IN | Off | Key In/Off | Inactive | Inactive |
Accessory | Accessory | Key Out/ACC | Active | Inactive |
Run | Run | Run | Active | Active |
Start | Crank Request | Crank | Inactive | Active |
Circuit/System Testing |
Important | ||
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing. |
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1. |
Verify the B+ fuse to the ignition switch is not open.
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2. |
If the fuse is open, test the following circuits at the ignition switch for a short to ground. If all circuits test normal, replace the BCM.
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B+ - terminal 1
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Ignition - terminal 2
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Ignition - terminal 4
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Ignition - terminal 5
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Ignition - BCM terminal 19, X4
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Accessory Wakeup Serial Data - BCM terminal 21, X4
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3. |
Disconnect the Key In Switch harness connector.
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4. |
Ignition OFF, test for less than 5 Ω of resistance between the Key In Switch terminal 1 and terminal 2.
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5. |
If greater than the specified range, replace the Key In Switch.
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6. |
Ignition OFF, key out, test for infinite resistance between the Key In Switch terminal 1 and terminal 2.
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7. |
If less than the specified range, replace the Key In Switch.
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8. |
Connect the Key In Switch harness connector.
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9. |
Disconnect the ignition switch harness connector.
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10. |
Test for battery positive voltage between the battery positive voltage circuit of the ignition switch and ground.
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11. |
If not the specified value, test the circuit for an open/high resistance.
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12. |
Perform the ignition switch component test. The test should pass. |
13. |
If the ignition switch fails, replace the ignition switch.
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14. |
Ignition OFF, disconnect BCM connector X1, test for less than 1 V between the following ignition circuits of the BCM and ground.
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terminal 2
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terminal 4
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terminal 14
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terminal 21
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If not the specified range, test the circuit for a short to voltage.
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16. |
Ignition key out, test for less than 1 V between the following ignition circuits of the BCM and ground.
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terminal 2
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terminal 4
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terminal 14
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terminal 21
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17. |
If not the specified range, test the circuit for a short to voltage.
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18. |
Disconnect the Key In Switch harness connector.
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19. |
Install a jumper wire between the Key In Switch terminal 1 and terminal 2.
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20. |
Test for less than 5 Ω of resistance between the BCM and the ignition switch on the following circuits.
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Ignition key resistor signal Terminal 4 and Terminal 6
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Off/Run crank Terminal 2 and Terminal 5
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Off/Run crank Terminal 2 and Terminal 3
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Accessory voltage Terminal 21 and Terminal 4
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Ignition 1 voltage Terminal 14 and Terminal 2
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21. |
If not the specified range, test the circuit for open/high resistance.
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22. |
Test for infinite resistance between the BCM ignition key resistor signal circuit terminal 4 and ground.
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23. |
If not the specified value, test the signal circuit for a short to ground.
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24. |
If all circuits test normal, replace the BCM.
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Component Testing |
Ignition Switch
Using the Resistance Test below, verify the resistance between the pins of the ignition switch match the chart below while cycling the key to each switch position listed.
Resistance Test
Ignition Switch Position | Pins 1 and 4 | Pins 1 and 2 | Pins 1 and 3 | Pins 5 and 6 |
Off Key Out | Infinite | Infinite | Infinite | Infinite |
Off Key IN | Infinite | Infinite | < 5.0 Ω | Infinite |
Accessory | < 5.0 Ω | Infinite | Infinite | Infinite |
Run | < 5.0 Ω | < 5.0 Ω | Infinite | < 5.0 Ω |
Start | Infinite | < 5.0 Ω | Infinite | 1275-1325 Ω |
Repair Instructions |
Perform the Diagnostic Repair Verification after completing the repair.
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Ignition and Start Switch Replacement
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Control Module References
for module replacement, setup, and programming
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