What is a ecm - Cars & Trucks

If everything plugged into the engine without changing anything I would try it with the cavaliers ECM there is a lot of vehicle specific information in it. These ECMs are not programable. I hope this helps you, take care

P0688 (generic) = ECM/PCM Power Relay Sense Circuit /Open
P0688 DODGE - Auto Shutdown Relay Control Circuit Low

Check all the ECM fuses, if the fuses are OK try replacing the ASD (Auto Shut Down) relay.

Read more: http://www.autocodes.com/p0688_dodge.html#ixzz405J7vpq8

Possible causes:

- Weak battery - Low voltage while cranking
- Faulty Engine Control Module (ECM) relay
- Blown ECM fuse
- Faulty ECM
- ECM harness is open or shorted
- ECM circuit poor electrical connection

Did you disconnect the negative battery cable before changing ECM? check ECM fuse, why did you change ECM in first place?

This type of work normally requires diagnostic or key coding equipment .

You can find a ecm at autozone but if not you can find one at the dealer, make sure that you handle this part with care, also make sure the ecm is ready to install, you need this things before installing the ecm latex gloves, you also need to ground your self to prevent any shock with ecm by doing this you need a wire with the one end to the ground of the car and the other end to your self you can buy one at autozone, NEVER TOUCH ECM WITH OUT GLOVES this is a very sensitive and delicate part, unplug the negative cable from battery then unplug all the wires from ECM unscrew the ecm and replace the new one, screw the new ecm plug in all the wires and connect the negative cable that's it your done good luck!!!!

passenger side Under dash on the side kick pad with 3 connector
To replace it .. unplug battery then remove connector at ECM on old ecm remove two screw and the plate remove both memory and install them in the new ECM....plug 3 connectors and battery cable

hope it help

it might be your ecm could be internal ,find out if there is anything else on that ecm fuse if its just the ecm ,you will need a ecm,check your wiring from fuse box to the ecm if the wiring is good then you should know what to replace

REMOVAL & INSTALLATION

Print

OPERATION

When the term Electronic Control Module (ECM) is used in this guide it will refer to the engine control computer regardless that it may be a Vehicle Control Module (VCM), Powertrain Control Module (PCM) or Engine Control Module (ECM).
The Electronic Control Module (ECM) is required to maintain the exhaust emissions at acceptable levels. The module is a small, solid state computer which receives signals from many sources and sensors; it uses these data to make judgments about operating conditions and then control output signals to the fuel and emission systems to match the current requirements.
Engines coupled to electronically controlled transmissions employ a Powertrain Control Module (PCM) or Vehicle Control Module (VCM) to oversee both engine and transmission operation. The integrated functions of engine and transmission control allow accurate gear selection and improved fuel economy.
In the event of an ECM failure, the system will default to a pre-programmed set of values. These are compromise values which allow the engine to operate, although at a reduced efficiency. This is variously known as the default, limp-in or back-up mode. Driveability is almost always affected when the ECM enters this mode.

REMOVAL & INSTALLATION

See Figures 1 and 2

Fig. Fig. 1: ECM mounting scheme-except 1996 models

Fig. Fig. 2: ECM mounting scheme-1996 models
The ECM is located in the passenger side footwell in the kick panel up to 1996. In 1996, the ECM is located in the engine compartment next to the battery.

1. Disconnect the negative battery cable.
2. Disengage the connectors from the ECM.
3. Remove the spring retainer off and over the rail of the ECM on vehicles except 1996.
4. Slide the ECM out of the bracket at an angle.
5. Remove the ECM.

To install:

1. Install the ECM into the bracket.
2. Install the spring retainer (except 1996) and plug in the electrical connectors.
3. Connect the negative battery cable.

Hello.

The ECM is mounted on the right side of the dash above where the passengers feet would be.
The lower panel will need to be removed to see it.
Here is the service manual procedure to remove it.

1. Turn ignition to "OFF".
2. Disconnect battery ground cable.
3. Remove right hand hush panel.
4. Disconnect connectors from the ECM
5. Remove ECM mounting hardware.
6. Remove ECM from the passenger compartment.
7. Remove ECM access cover.
8. Transfer PROM unit to replacement ECM. Using two fingers, push both retaining clips back away from the PROM. At the same time, grasp it at both ends and lift it up out of the socket. Do not remove the cover of the PROM. Use of unapproved PROM removal methods may cause damage to the PROM or socket.
9. Remove new ECM from its packaging and check the service number to make sure it is the same as the defective ECM.
10. Remove access cover.

There you are. I hope your repair goes well.

KL

change the crank sensor.No the ECM has no internal oil components