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Discussion Starter · #1 ·
Howdy all,
I purchased a not running 97 Cabrio ( OBD 2) and am not getting spark. No activation signal to the coil.
There is no bad Crank Sensor (Engine Speed ) Code or any others, but I think the CPS is the problem why there is no coil trigger from
the ECM. I also have a running 95 Cabrio ( OBD 1) mostly similiar but not the same.

I noticed on pin 1 and 3 of the CPS connector coming from the ECM ( CPS side pulled off ) on the
OBD 1 car I have about 4.5 volts with Key on engine off. On the 97 OBD 2 I only get about 1.6 volts.
It is the same CPS part number called out for on both ( BTW both cars are manual transmission ) so I would guess they would
supply the same voltage to the CPS. I have checked the voltage at the ECMs Pin 1 - Ground and Pin 54 ( Battery +) all in spec.
I also checked switched voltage (from ignition ) to pin 23 and it is working properly also. I have also ohmed out between the connector and ecm
that is all good .2 ohm and checked connector ground to back to battery negative also good.

I have used the original ECM that came with the car and two other used ( cheap ebay ones ) to also test.
All of them put out the same voltage about 1.6v on OBD 2 ECMs. I find it hard to believe ( but maybe it is a common failure ) that I have 3 bad ECM s ?
Am I missing something ?

My main questions are 1) on an OBD2 should the voltage at pin 1 and 3 of the Crankshaft posistion sensor be about 4.5 volts like the OBD 1
or did they change something in the OBD 2 that it uses only about 1.6 volts ?

2) Are there any other practical things I can check at the ECM for inputs or at / in the ECM itself ?

3) Has anyone pulled apart these ECMs with any advice of possible bad components things I can check / possibly fix ?

Any suggestions or relevant information is greatly appreciated.

Thanks in advance for you time and input.
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