Location modulator valve - 1994 GMC Sierra

Question edited for clarity.
Question moved to model category.

It is not a computer box, it is a mechanical valve. This is it.

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That is part of the ABS system and it is on the modulator. The modulator is the block with all the brake lines connecting to it near the firewall on the drivers side under the hood.

Please verify the year of your truck. A 2003 Chevy Trailblazer has a 4L60E transmission. This transmission does not have a vacuum modulator valve. The 4L60 uses a vacuum modulator valve but the last year for that transmission was 1992. The perpose of the modulating valve is to control/regulate line pressure. The line pressure in a 4L60E is computer controlled or controlled electrically.

The Exhaust Gas Recirculation valve does just what the name implies: it diverts some exhau st gases back into the intake system at low engine speeds. This lowers combustion temperature to reduce NOx levels. It also reduces throttle response and bottom-end power.
Disabling the EGR valve is easy. Locate the valve and the EGR vacuum modulator valve (two gold-colored metal stampings, usually at the rear of the engine). The EGR valve has steel lines leading to it from the exhaust manifold. The EGR vacuum modulator has two vacuum lines between it and the intake manifold and a third vacuum (soft) line between the modulator and the EGR valve itself.
EGR Vacuum Modulator
EGR valve (arrow) is shown adjacent tosimilar EGR vacuum modulator valve. EGR valve is connected to exhaust manifold with steel lines. Modulator has vacuum lines only.
Disconnect the vacuum line between the valve and modulator and place any solid object of appropriate size (dowel, etc.) in the line, then reconnect the line. Or you can get a EGR block off plate

Error Code: P0130
Fault:
Oxygen Sensor (O2S) 1, Bank 1 - Circuit Malfunction
Possible Cause:
Malfunction Indicator Lamp (MIL) Triggered on first occurrence.
-Wiring harness.
-Oxygen sensor (O2S).
-Engine control module (ECM).

Error Code: P0505
Fault:
Idle Speed Control (ISC) System - Malfunction
Possible Cause:
-Wiring harness.
-Idle speed control (ISC) actuator/Idle air control valve (IAC) valve.
-Throttle motor.
-Throttle valve tight/sticking.
-Engine control module (ECM).

Error Code: P0100
Fault Location:
-Mass Air Flow (MAF) Sensor/Volume Air Flow (VAF) Sensor - Circuit --Malfunction
Possible Cause:
-Wiring harness.
-Mass air flow (MAF) sensor.
-Volume air flow (VAF) sensor.
-Engine control module (ECM).

Error Code: P1491
Fault:
Exhaust Gas Recirculation (EGR) Valve Insufficient Lift
Possible Cause:
-Wiring harness.
-EGR Valve.
-ECM

Error Code:P1607
Fault:
-Engine Control Module (ECM)/Powertrain Control Module (PCM)

Error Code: P0966
Location:
-Pressure Control (PC) Solenoid B - Circuit Low
Possible Cause:
-Wiring short to earth.
-Pressure control (PC) solenoid.
-Engine control module (ECM)/Powertrain control module -(PCM)/Transmission control module (TCM) .

doesnt have one electronic internal valve

{: ) The ABS/TCS module (or the Electronic Brake Control Module- EBCM ) is located at the front left lower corner of the engine compartment, under the air cleaner housing. The EBCM is attached to the brake pressure modulator valve. See sample diagram:


1. secondary air injection
2. Electronic Brake Control Module
3. brake pressure modulator valve

Hello, the 2003 impala's dont have a transmission modulator valve. this transmission is electronic controlled by the power train control module. the transmission uses a pressure control sol. inside the transmission instead of a vac. operated modulator valve. if you are having a late harsh shifting problem, this would be more in the area of a pressure control sol. at fault

It is located on the transmission with a vaccume line going to it. There is a clamp with a bolt that holds it to the transmission. It is an easy fix.

if u mean the vacuum modulator valve, it doesn't have one, it is an electronically controlled transmission, what is the problem with trans?