P1645 - 1996 Riviera, and high trans temp

Hey everyone,

So first off my car seems to have a slight surge at idle (roughly 100rpm), and my car is giving me a code of P1645. I have no idea what the code is though. I thought maybe this is a purge solenoid issue or something. I also have my abs/trac control light on but I assumed that was a wheel speed sensor (unless this is the P1645 code im getting). Anyone know what this code means or indicates?

Also my car has a 4t60e-hd and the normal operating trans temp should be 180-200 according to the manual. But occasionally if Im stuck in slow traffic or even run through a drive through in town and then get back on the road, my trans temp will touch 210-215. Im not sure why, unless its a weak torque converter as my car seems to have the common "shudder" when lugging/low rpm locked up in 4th. Any thoughts??

Thanks!

And as of tonight, I am now getting a P1406 code which I think is egr related..

DTC P1635 5 Volt Reference Circuit
Refer to 5 Volt Reference A.

Circuit Description
The PCM uses the 5 Volt Reference A circuit as a sensor feed to the following sensors:

•The TP sensor.
•The MAP sensor.
•The EGR Valve Pintle Position sensor.
The PCM monitors the voltage on the 5 Volt Reference A circuit. If the voltage is out of tolerance, the PCM will set DTC P1635.

Conditions for Setting the DTC
•The PCM detects a voltage out of tolerance condition on the 5 Volt Reference A circuit.
•The above condition is present for longer than 19 seconds.
Action Taken When the DTC Sets
•The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
•The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
Conditions for Clearing the MIL/DTC
•The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
•The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
•The DTC can be cleared by using the scan tool.
Diagnostic Aids
Important:: Be sure to inspect PCM and engine grounds for being secure and clean.

Check for the following conditions:

•Poor connection at the PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
•Damaged harness. Inspect the wiring harness for damage.
•If the harness appears to be OK, observe the MAP display on the scan tool with the ignition ON, engine not running while moving connectors and wiring harnesses related to the following sensors. A change in the MAP display will indicate the location of the malfunction.
– The TP sensor.
– The MAP sensor.
– The EGR valve.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

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

5.A malfunctioning EGR valve can leak a small amount of current from the ignition feed circuit to the 5 volt reference A circuit. If the problem does not exist with the EGR valve disconnected, replace the EGR valve.
13.This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

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DTC P1406 Exhaust Gas Recirculation (EGR) Position Sensor Performance

Circuit Description
The PCM monitors the EGR valve pintle position input to ensure that the valve responds properly to commands from the PCM and to detect a malfunction if the pintle position sensor and control circuits are open or shorted. If the PCM detects a pintle position signal voltage outside the normal range of the pintle position sensor, or a signal voltage that is not within a tolerance considered acceptable for proper EGR system operation, the PCM will set DTC P1406.

Conditions for Setting the DTC
•EGR Feedback is less than 0.14 volt at any time.
OR

•EGR Feedback is 0.4 volt greater or less than the EGR Closed Valve Pintle Position when the Desired EGR Pos is commanded to 0%.
OR

•Actual EGR Pos is 10% greater or less than the Desired EGR Pos.
•Any of the above conditions present for longer than 20 seconds.
Action Taken When the DTC Sets
•The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
•The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
Conditions for Clearing the MIL/DTC
•The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
•The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
•The DTC can be cleared by using the scan tool.
Diagnostic Aids
Check for the following conditions:

•Open EGR ignition filter circuit.
An open in the EGR ignition filter circuit will cause erratic EGR Position Error readings while the EGR valve is operating. With the ignition ON, a test light should illuminate when connected between ground and the EGR ignition filter circuit at the PCM connector. If not, locate and repair the open in the EGR ignition filter circuit.

•Excessive deposits on EGR valve pintle or seat.
Check for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.

•Poor connection or damaged harness.
Inspect the wiring harness for damage. If the harness appears to be OK, observe the EGR actual position display on the scan tool while moving connectors and wiring harnesses related to the EGR valve. A change in the display will indicate the location of the malfunction.

•EGR Valve Icing.
EGR valve icing can occur during cold ambient conditions. An EGR valve icing condition will affect EGR system operation by causing the pintle to stick in the closed position. If DTC P1406 sets, EGR system operation may be inhibited for the remainder of the trip.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Chances are, your EGR valve is jacked up causing the P1645, and it finally got bad enough to set the P1406.

How are you monitoring trans temp? There is no trans temp gauge in the car. If you're referring to the coolant temp, then that's believable considering a bad EGR valve can cause the engine to run hotter than normal.

Hey thanks for the response, so I have an aeroforce scan gauge that I've been watching trans temp with.