: 98 STS Codes

08-23-04, 07:13 PM
I have these codes. What do I do to fix this stuff. And what exactly do they mean??

P1579 - P/N to D/R at High Throttle Angle - Power Reduction Mode Active
U1064 - Loss of Communications with DIM
B1343 - Air Inlet Door Movement Fault

I have no engine lights on and the car runs fine, but these three keep popping up.

08-27-04, 12:21 AM

Circuit Description

This diagnostic test is used to detect the vehicle transaxle being placed in gear under conditions that may cause damage to the vehicle powertrain or create an unsafe condition. When such a condition exists, DTC P1579 is set and engine power will be reduced by disabling fuel to individual cylinders.

Conditions for Running the DTC

DTCs P0122 and P0123 not set.

Conditions for Setting the DTC

* Gear selection from Park or Neutral to Drive or Reverse.
* Vehicle speed less than 6 MPH.
* Engine speed greater than 2000 RPM.
* Throttle angle of 20 degrees or greater.

Action Taken When the DTC Sets

PCM will retard spark and disable fuel to individual cylinders to reduce engine power.

* The Malfunction Indicator Lamp (MIL) will not illuminate.
* The PCM will command a message to be displayed.
* The PCM may record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records.

Conditions for Clearing the Message/DTC

* The PCM will turn the message OFF after one run and pass of the diagnostic test.
* A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.
* A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
* 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. See: Vehicle On-Board Diagnostics (Accessing and Clearing Codes)\Clearing Diagnostic Trouble Codes

Diagnostic Aids

If the drivers actions caused this DTC to set, clear the DTC and inform customer of proper shift procedure.

Manipulate the wire harness while watching the scan tool display looking for opens and shorts.

Reviewing the Failure Rec. may help diagnose an intermittent failure by showing how long ago and under what conditions the DTC set.

U1064 ( I GET Thie One a lot too)

The class 2 serial data line communicates information between modules. Each module connected to the serial data line is assigned a recognition code, or address. This code is used in order to identify which modules are communicating. Modules communicate with each other by periodically sending State Of Health (SOH) messages. When the ignition switch is in RUN, each module communicating on the serial data line sends a SOH message every 2 seconds . This ensures that the system is operating properly. When the Dash Integration Module (DIM) stops communicating on the class 2 serial data line, the SOH that is normally sent on the serial data line every 2 seconds disappears. The module, which expects to receive that message, detects the absence of the message. The module in turn sets DTC U1064 associated with the loss of SOH of the DIM.


* The module does not receive a state of health (SOH) message back from the DIM. The module retries the request 3 times, and then sets DTC U1064.
* This DTC only sets if U1300 or U1301 is not current.


* DTC U1064 is stored in the module.
* The module uses the default values for the initialization data.
* This DTC does not cause driver warning message to appear.


* This DTC clears (status changes from current to history) under any of the following conditions:
* The module detects a state of health message from the DIM.
* At each ignition cycle.
* A history DTC clears after 50 consecutive ignition cycles if the Conditions for setting DTC are no longer present.
* Current and history DTCs may be cleared using a scan tool.


* DTC U1064 does not normally represent a failure within the module.
* When loss of class 2 serial data communication DTCs (DTCs with the letter ~i as the prefix) are stored as history DTCs, know all possible serial data DTCs set in each module before diagnosing the serial data line.
* If U1064 is stored in the module memory, inspect for the same DTC stored in other modules capable of storing this DTC.
* If the DTC is a history DTC, the problem may be intermittent.

The numbers below refer to the step numbers on the diagnostic table:

2. U1064 is the result of loss of communication with the dash integration module (DIM). Note that other modules on the class 2 serial data line may also set U1064 if the DIM is not communicating with the serial data line.

4. Clear all DTCs after the repair procedure is complete.


The rear fuse block supplies ignition voltage through circuit 141 (BRN). The Instrument Panel Module (IPM) commands the actuator to move by supplying voltage on the command circuit 1614 (DK GRN). The command line voltage and motor actions are as follows:

* 0 volts moves toward outside air.
* 2.5 volts stops the motor.
* 5 volts moves toward full recirc.

The IPM determines the current position by monitoring the voltage on the feedback circuit 1838 (PPL). A feedback potentiometer supplies a regulated 5 volt signal by the IPM on circuit 705 (GRY), and a ground from the IPM circuit 1791 (YEL). The pot is gear driven inside the actuator. The feedback voltage is a function of the motor position with a high voltage of 4-5 volts indicating full recirc door position. A low voltage of less then 1 volt indicates the full outside air position. Operation of the air mix door actuator can be evaluated through Scan Tool data.


* Ignition is ON.
* Feedback circuit is open or shorted.


* A default value of 128 counts will be used by the IPM.
* This default value results in only two positions of the actuator full outside air and full recirc air being used by the system.


* Using a Scan Tool.
* A current DTC will clear when the diagnostic runs and does not fail.
* IPM battery voltage is interrupted.

The numbers below refer to the step numbers on the diagnostic table.

1. Perform the Body Control Module Diagnostic (BCM) Diagnostic System Check before continuing with the diagnosis of this DTC.
2. This test allows the Scan Tool to recalibrate the actuator.

11. Determines if the Instrument Panel Integration Module (IPM) is malfunctioning.

14. Determines if the actuator is operational.

I can't paste the images on here which contain further diag info but this should help a little.

08-27-04, 01:20 AM
Wow, thanks for that. Even though it's very technical. I'm sure If I read it again I can figure it out. Thanks.

01-03-06, 09:28 PM
Wow, thanks for that. Even though it's very technical. I'm sure If I read it again I can figure it out. Thanks.

WOW old post but I thought maybe you could tell me what you found for a fix in regards to B1343 - Air Inlet Door Movement Fault. mine is doing the same thing and the driver's side air outlets are warmer than the passenger's when the AC is on. I'm guessing the door is stuck. LOL..wher ethe hell is it?? :D