GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1999 🢒 Aurora 🢒 DTC 🢒 DTC P1640 Driver-1-Input High Voltage

Circuit Description

The PCM contains chips called Output Driver Modules that provide 7 switchable ground outputs for operating solenoids, relays, telltales, and other devices. Each of these ground outputs has fault lines that feed back to the PCM's microprocessor. ODM #1 can also sense high voltage coming in which might damage the chip. DTC P1640 is used to monitor ODM #1's overvoltage sense line.

Conditions for Running the DTC

Engine running at least 10 seconds.

Conditions for Setting the DTC

Overvoltage is sensed for 2 seconds.

Action Taken When the DTC Sets
    •  The PCM will illuminate the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
    •  The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.

Conditions for Clearing the MIL/DTC
    •  The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
    •  A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
    •  A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.
    • Use a scan tool to clear DTCs.
    • Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in Powertrain Control Module Description .

Diagnostic Aids

Since an overvoltage at ODM #1 should also trigger DTC P0563, the diagnosis for DTC P0563 may be used if vehicle voltage is actually too high.

A loose or faulty connection at generator L terminal may cause DTC P1640 to set intermittently.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

  1. Checking if DTC P0120 is also set. If it is, go there first because it may help to pinpoint a faulty TP sensor.

    2.

  2. Checking for an intermittent short to voltage in the TP sensor 5 volt reference circuit or the TP sensor signal circuit that may be causing a high TP input.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Turn the key ON.

Is DTC P0120 or P0123also set?

--

Go to DTCs that are set

Go to Step 3

3
  1. Record fluid life indexes, turn the key to OFF and wait 30 seconds.
  2. Disconnect PCM connector C1.
  3. Examine terminals 7, 62 and 68 of C1.
  4. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis

Go to Step 4

4
  1. Disconnect Throttle Position (TP) sensor connector.
  2. Examine all TP sensor connector terminals.
  3. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis

Go to Step 5

5

  1. Check the TP sensor ground circuit for possible open.
  2. Check the TP sensor 5 volt reference circuit or the TP sensor signal circuit for possible short to voltage.
  3. Repair circuit(s) if needed.

Was a repair made to any circuit?

--

Go to Powertrain Control Module Diagnosis

Fault not present. Go to Diagnostic Aids