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Discussion Starter · #41 ·
At this point, I'd be checking the connector for both the Hall effect sensor into the PCM, and the ASD out of the PCM.

If you jump pin #51 to ground, will the motor then start?

If the connectors are good in the housing (not loose on the pins!), I'd have to say you've just about beat it down to the PCM, as rare as PCM failures actually are.

But one more thing I'd suggest.

With the negative battery cable disconnected from the battery, remove/reinstall both connectors on the ECU three to four times.

Then reconnect the negative battery cable to the battery, and see if it runs.

RwP
I trying and nothing , still no spark
 

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. . . .I trying and nothing , still no spark . . .
Did you perform the actions with the electrical connectors as contributor RalphP suggested in post #39?

Two functions that the PCM must perform when it receives the pulsing signal from the distributor. It grounds the circuit at pin #51 so he ASD relay will provide 12 volt power at the coil, the electric fuel pump runs, and other devices are powered. It also uses the pulsing signal to determine when to interrupt the electrical current flowing through the primary circuit of the coil. This interruption induces the high voltage spark in the coll which travels to the appropriate spark plug through the distributor cap and rotor. The PCM is not performing either function. So it needs to be replaced.
 

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Discussion Starter · #43 ·
Did you perform the actions with the electrical connectors as contributor RalphP suggested in post #39?

Two functions that the PCM must perform when it receives the pulsing signal from the distributor. It grounds the circuit at pin #51 so he ASD relay will provide 12 volt power at the coil, the electric fuel pump runs, and other devices are powered. It also uses the pulsing signal to determine when to interrupt the electrical current flowing through the primary circuit of the coil. This interruption induces the high voltage spark in the coll which travels to the appropriate spark plug through the distributor cap and rotor. The PCM is not performing either function. So it needs to be replaced.
Okay i take for manual or automatic transmission PCM ?
 

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. . . .Okay i take for manual or automatic transmission PCM ? . . .
I would think you would want a PCM designated for same engine but with a manual transmission. The PCM for automatic transmission would have additional circuitry for the lockup torque converter solenoid. If circuitry not present then you would have a constant CHECK ENG lamp illuminated. Hopefully the only differences in the internal PCM logic for the same engine is just the particular transmission????
 

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My 89 has two circuit boards.
The bottom circuit board has a part number clearly visible through the potting.

In 2004 or so, This part number corresponded with RockAuto and Cardone's listing for a manual transmission, yet mine is an Automatic.

I did not discover this until 2 separate computers failed to initiate overdrive/lockup.

When I ordered the 'manual transmission' ECM, all worked as it should.

RA never returned my extra shipping money, but they and Cardone did correct the part number switch up shortly after.

Never any check engine light with the manual ecm in the automatic vehicle.

Bust out your torx bits and look for a part number on the ECM's circuit board through the potting, and try and get that specific ECM, if available.
Had I done this initially, it would have saved me time, money, anxiety and stress.
 

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Discussion Starter · #47 ·
My 89 has two circuit boards.
The bottom circuit board has a part number clearly visible through the potting.

In 2004 or so, This part number corresponded with RockAuto and Cardone's listing for a manual transmission, yet mine is an Automatic.

I did not discover this until 2 separate computers failed to initiate overdrive/lockup.

When I ordered the 'manual transmission' ECM, all worked as it should.

RA never returned my extra shipping money, but they and Cardone did correct the part number switch up shortly after.

Never any check engine light with the manual ecm in the automatic vehicle.

Bust out your torx bits and look for a part number on the ECM's circuit board through the potting, and try and get that specific ECM, if available.
Had I done this initially, it would have saved me time, money, anxiety and stress.
Yes i will the oem number on my PCM … but a looking on RockAuto and is not available:(
 
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