Circuit Description
The transmission control module (TCM) provides voltage to shift solenoid 1, 2, and 3 (SS1, SS2, and SS3) and pressure control solenoid 2 (PCS2) through a separate solid-state device called high side driver 2 (HSD2). HSD2 is continuously ON during normal operation, except during a brief circuit test. The TCM regulates control current to the solenoids by switching the appropriate low side driver ON and OFF.
DTC P2670 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2670 Actuator Supply Voltage 2 Low
Conditions for Running the DTC
| • | The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts. |
| • | HSD2 is commanded ON. |
Conditions for Setting the DTC
DTC P2670 sets when the TCM detects a low voltage condition, less than 6.0 volts, in 3 solenoids in the HSD2 circuit.
Action Taken When the DTC Sets
| • | The TCM illuminates the malfunction indicator lamp (MIL). |
| • | If the failure occurs while in a forward range, a shift to 1st, 3rd or 5th range is made. |
| • | While diagnostic response is active, if the shift selector is moved to NEUTRAL, the transmission will shift to NEUTRAL. If the shift selector is moved to REVERSE, the transmission will shift to REVERSE. If the shift selector is moved to a forward range or to REVERSE and the transmission is compromised by overspeeding or direction change, the transmission will shift to NEUTRAL. |
| • | DTC P2670 is stored in TCM history. |
| • | The TCM inhibits main modulation (MAIN MOD). |
| • | The TCM freezes shift adapts. |
| • | The TCM inhibits torque converter clutch (TCC) engagement. |
Conditions for Clearing the MIL/DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
| • | Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions: |
| - | A bent terminal |
| - | A backed-out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | You may have to drive the vehicle in order to experience a condition. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value | Yes | No |
|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data. Is voltage within the specified value? | 9-18 V | Go to Step 3 | Go to DTC P0562 for low voltage or DTC P0563 for high voltage |
Is the voltage within the specified value? | B+ | Go to Diagnostic Aids | Go to Step 4 | |
4 |
Is the voltage within the specified value? | B+ | Go to Step 5 | Go to Step 7 |
5 |
Is the voltage within the specified value at each solenoid terminal? | B+ | Go to Step 6 | Go to Step 8 |
6 | Test the PCS2 and the SS1, SS2 and SS3 for an open or shorted condition. Refer to Temperature Versus Resistance Solenoid. Refer to Testing for Continuity and Testing for Short to Ground . Did you find a condition? | -- | Go to Step 9 | Go to Step 10 |
7 | Test the HSD2 circuit between the TCM and AT inline 20-way connector for an open or short to ground. Refer to Testing for Continuity and Testing for Short to Ground . Did you find and correct the condition? | -- | Go to Step 11 | -- |
8 | Replace the AT internal wiring harness. Refer to Wiring Harness Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
9 | Replace the open or shorted solenoid. Refer to Control Valve Solenoid Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
10 |
Important: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM. Replace the TCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | -- | Go to Step 11 | -- |
11 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 12 | Go to Step 2 |
12 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
