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BigBob, Shop manager/technician
Category: Chevy
Satisfied Customers: 4838
Experience:  Shop Manager with 25 years experience
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What is the physical location of the ECM for a 1993 chevy suburban.

Customer Question

What is the physical location of the ECM for a 1993 chevy suburban. 350 engine
Submitted: 7 years ago.
Category: Chevy
Expert:  BigBob replied 7 years ago.

It is Behind Right Hand Side Of Instrument Panel.


Let me know if i can help further,
Customer: replied 7 years ago.

Duralast / Electronic Spark Control Module For your 1993 Chevrolet Truck C2500 3/4ton Sub 2WD 5.7L TBI 8cyl


This appears different than what you sent me. Does this control the pulse for the injectors?

Expert:  BigBob replied 7 years ago.
I need to have your vin# XXXXX what type of transmission do you have, I do not think your vehicle has one of those. i will be back in about an hour, i will check back then.

Customer: replied 7 years ago.


Automatic 4 speed

Expert:  BigBob replied 7 years ago.

The control module is the control center of the fuel injection system. It constantly looks at the information from various sensors (inputs) and controls the systems (outputs) that affect vehicle performance. The control module also performs the diagnostics of the system. It can recognize operational problems, alert the driver through the Malfunction Indicator Lamp (MIL ) "Service Engine Soon" light on the instrument panel and store a Diagnostic Trouble Code(s) (DTC ) in the control module memory. The DTC identifies the problem areas to aid the technician in performing repairs.

The control module is an electronic computer designed to process the various input information, and send the necessary electrical response to control fuel delivery, spark control, and other emission control systems. The control module can control these devices through the use of Quad Driver Modules (QDM). When the control module is commanding a device or a component "ON," the voltage potential of the output is "LOW" or near zero volts. When the control module is commanding a device or component "OFF," the voltage potential of the circuit will be "HIGH," or near 12 volts. The primary function of the QDM is to supply the ground for the component being controlled.

The input information has an interrelation between sensor output. If one of the input devices failed, such as the oxygen sensor, this could affect more than one of the systems controlled by the computer.

The control module has two parts for service:
  • Controller which is the control module without the PROM (MEM-CAL).
  • PROM (Programmable Read Only Memory) which is a separate memory calibrator unit
Learning Ability
The control module has a "learning" ability which allows it to make corrections for minor variations in the fuel system to improve driveability. If the battery is disconnected, to clear diagnostic trouble codes or for other repairs. the "learning" process resets and begins again. A change may be noted in the vehicle's performance. To "teach" the vehicle, ensure the engine is at operating temperature. The vehicle should be driven at part throttle, with moderate acceleration and idle conditions until normal performance returns.

NOTE The control module must be maintained at a temperature below 85°C (185°F) at all times. This is most essential if the vehicle is put through a baking process. The control module will become inoperative if it's temperature exceeds 85°C (185°F). It is recommended that temporary insulation be placed around the control module during the time the vehicle is in a paint oven or other high temperature processes.

This is talking about the part you uploaded to me.

Knock Sensor System

All gas engines are equipped with a knock sensor system. A knock sensor is mounted on the engine block. On vehicles with a manual transmission, the sensor is connected by a blue wire to the knock sensor module, which is bracket mounted on the top of the engine. The sensor, in response to engine knock, sends a signal to the module and from there to the ECM, located in the passenger compartment. The ECM sends a signal to the distributor to retard timing.

If the vehicle is equipped with an automatic transmission (4L80E or 4L60E), a PCM (powertrain control module) is used instead of an PCM. The PCM performs all ECM functions and also provides electronic control for the transmission. It is located in the same place as the ECM.

NO knock sensor module is used on a vehicle equipped with a PCM. Instead, the blue wire from the knock sensor is wired directly to the PCM.

You do not have one of the modules you showed me, where did you get the picture? why do you think that is the problem?

Customer: replied 7 years ago.
from autozone online. One of the the previous emails from just answer had a wiring diagram which showed the pulses to the injectors coming from the ecm. When i checked for the part this is what came up. $72.00. Does the wires from the injectors, blue and green on one and red and white on the other go back to the PCM which is located in the passenger compartment. The problem seems to be intermittant. Checked to see if I had a pulse with noid light. I saw the light pulse and I hooked back up the injectors. Truck ran for about 5 minutes then died. Checked for pulse to the enjectors and the noid light did not come on.
Expert:  BigBob replied 7 years ago.
Lets start from the beginning. So you are getting no spark? Does the truck crank no start with no spark?

Customer: replied 7 years ago.

1. The vehicle is a 1993 chevy suburban with a 350 engine. The problem appears to be it is not getting fuel. I also have a 1988 chevy silverado with the same 350 engine.

2. The engine died on the 1993 and after extended periods of time it would start and run for approx. 5 minutes then die.

3. We cracked the fuel line at the carbuator and had fuel flow when the key was turned on. We assumed this elimated the fuel filter and pump.

4. We checked for spark at the coil and thought we did not have any. We replaced the coil and verified we had spark.

5. We removed the air breather and could see fuel being sprayed into the carbuator from the injectors when the truck would run but did not have any fuel when the truck died.

6. We swapped the injectors between the 1993 and the 1988 engines. The 1988 truck ran normal and the 1993 truck continued with the same problem.

7. We swapped the fuel injector pressure regulator. The 1988 ran fine and the 1993 continued with the same problem.

8. We swapped the fuel pump relay with the same results.

9. We got a noid light from autozone and when the truck ran we had pulse. When the truck died we no longer had pulse.

10. During a previous e-mail with just answer and a different technician a wiring diagram was attached. The diagram showed the ECM controlled the injectors. The explanation was the injectors were controlled by applying a ground at a pulse which lifted a ball valve allowing fuel through the injector.

11. When I searched autozone parts the electronic spark control came up. When I talked to autozone it is supposed to be located in the distributor. When we pulled the distributor cap we did not find anything which looked like the picture.



Expert:  BigBob replied 7 years ago.
Ok I got it now. I think your problem is in the distributor or pickup coil, which is in the distributor. The computer is not needed to create spark, however it can cause it to not occur. Do these tests.

1. Disconnect the 4 wire connector from the Ignition Control Module (ICM). Verify no spark. 2. Verify there is ignition power to the coil and distributor during cranking. 3. Use a test light from B+ to coil negative, check for a blinking test light during cranking. 4. If none there, disconnect the pick up coil from the module. Verify the pick up produces at least 750 mV of AC voltage during cranking. If it does not, replace the pick up coil and distributor shaft. 5. If it does, replace the module.