Circuit Description
Battery positive voltage is supplied at all times to the seat adjuster switch and the memory seat module (MSM)/driver position module (DPM) through the same circuit. The MSM/DPM uses this battery voltage input to determine if battery positive voltage is applied to the seat adjuster switch.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1420 Device Voltage
Conditions for Running the DTC
The MSM/DPM must be powered and cannot have B1327 - Battery Voltage Low as an active DTC for this DTC to set.
Conditions for Setting the DTC
This DTC will set only when the MSM/DPM detects less than 3 volts from the circuit.
Action Taken When the DTC Sets
| • | Current and history codes are set. |
| • | The MSM/DPM ignores all memory recall commands. |
| • | All manual seat functions will operate. |
Conditions for Clearing the DTC
| • | The DTC will clear when the MSM/DPM detects that the voltage from the circuit is greater than 3 volts. |
| • | The MSM/DPM will clear the history DTC after 50 fault free ignition cycles. |
Diagnostic Aids
The MSM is also known as the DPM for this vehicle.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Driver Seat Schematics Connector End View Reference: Power Seat Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 | Activate any one of the power seat adjuster switches. Does the seat move in the commanded direction? | Go to Step 3 | Go to Step 4 |
3 | Probe the battery positive voltage circuit of the memory seat module (MSM)/driver position module (DPM) connector C2 Pin-F11 with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 5 | Go to Step 6 |
4 | Test all of the power seat switch signal circuits between the seat adjuster switch and the MSM/DPM for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
5 | Inspect for poor connections at the harness connector of the MSM/DPM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
6 | Repair the open in the battery positive voltage circuit of the MSM/DPM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 9 | -- |
7 | Repair the short to ground or open in the battery positive voltage circuit of the MSM/DPM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 9 | -- |
8 | Replace the MSM/DPM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | -- |
9 |
Does the DTC reset? | Go to Step 2 | System OK |
