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Amedee, Former ASE Master Tech
Category: Car
Satisfied Customers: 26463
Experience:  ASE certified tech advanced level specialist. Wisconsin certified emissions state inspector
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Isuzu Rodeo: I am trying to read an ECM

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I am trying to read an ECM on a 99 Isuzu Rodeo. I have a Solus pro amd it is not able to read the ecm. Any ideas?


Did you still need help?

Does the vehicle start and run?

Does the check engine light come on with the key on?

Does the TPS have 5 volts going to it with the key on?
Customer: replied 5 years ago.



engine just rebuilt, so still no


no check eng light


actually, dont know. which port would that be?

I know the port has 12v power for the reader turns on.


Start by checking to see if the throttle position sensor has 5 volts going to it with the key on. This is a check to be sure that the computer is awake with the key on.

Another thing you can check for is power down at pin 16 of the diagnostic connector under the dash. This should have power on it when the key is turned to the "on" position.

If these do not past the tests, we need to check all powers and grounds going into the computer with the key on.

Going to get some sleep. Run these tests and reply back tomorrow with the results.

I will be looking forward to your reply!
Customer: replied 5 years ago.

Pin 16 is the HOT all the time. and i have that and ground


the throttle position sensor has 2.6v not 5v


I hope your online now.


Temp outside is great, but it is wet. LOL


Also, want to make sure. the TPS is located on driver side of throttle body?

It sounds to me like you could have a bad ECM. You will have to check the inputs into the ECM before replacing it.

The ECM powers are the red/blue wire going into pin 15 and 16 on connector 3

The red/white wire going into pin 4 on connector one.

The TPS will have a red wire, green wire and blue wire going to it.
Customer: replied 5 years ago.

sorry, got wrong power setting


the throttle position sensor has like 7v not 5v, thou i have charger on vehical now. batt is at 9v. something is draining batt. find that later


wait a second. when i check pin 16 it had 12v.

If the battery voltage is only at 9 volts, how can pin 16 of the diagnostic connector have 12 volts?
Customer: replied 5 years ago.

I read 12, not sure. anyway. I might have a ground problem. I just rebuilt the engine and it turns out the reason for no crank is do to this motor has no ground strap.


YES.. if there is no ground to the engine, then the starter will not be able to engage.

IF you have not done so already, clean and re attach all grounds.

If the communication with the ECM still is no longer present, then you will have to check the grounds going into the ECM with the key on.
Amedee and other Car Specialists are ready to help you
Customer: replied 5 years ago.

all right. i will let you know what happens.

Sounds good!
Customer: replied 5 years ago.

I can read the ECM now. I am surprise a ground can cause so much issues.

YUP! That will do it!

Glad to hear it is now working.