fireburdluvr85

Taken on my moms 92z to get her rolling after sitting in a yard for 7 years. 350 tpi full exhaust with cats. Figured this is relevant.
After fixing multiple driveability issues I attempt to plug my MODIS to confirm sensors and other data looks OK to me. All I get is no communication. I checked all fuses. I checked to make sure I have good ground and 12v constant at the aldl connector. Nothing out of the ordinary.
Moms b/f added an aftermarket alarm and radio but I verified that shoddy wiring aside, it didn't interfere with the ecm.

The ecm was swapped at some time for an 89z24 ecm which is a '730 ecm.
The b/f isn't very auto savy, he's a part changer. Lol

Help!!!

L98_383_Stroker

What voltage do you see on pin M? That is the data pin. On 8192 baud cars, they typically set at +5V waiting for the scan tool to send a message.

Also, does shorting pins A&B get the ECM to flash codes? That might help to determine if the ECM is bad.

fireburdluvr85

I'll check that this evening. I did have a positive voltage less then 12v on pin m. I'll verify exact tho

fireburdluvr85

I only get code 12 flashed when jumped. Sorry for the late response. Taking work while I can so no time to go fiddle with the car often

L98_383_Stroker

If you are getting code 12, I would think your ECM is okay. I think the only way to troubleshoot your issue is to hook an oscilloscope to the ALDL line and see what is going on. Your scan tool should be sending a short message to the ECM requesting a data packet. If you don't see that message traffic, I would suspect the scan tool. Are there multiple ALDL connectors for the MODIS? Some ALDL cars have data on pin E and some have data on pin M. I don't know how the MODIS handles that. The cars with data on pin E are 160 baud and don't require the scan tool request message. Cars with the data on pin M are 8192 baud and require the message request.

fireburdluvr85

Yes each type of car has its own connector. Then you select the year. Are the pins on the 89 '730 ecms the same as 92 '730 ecms? Again, I didn't swap parts. I'm trying to procure the original ecm from the car since it was saved. I believe the original problem for the swap was vats issues. Lol. Damn lazy people

I'm familiar with the '165 ecm and the '411. I never messed with the '730.

fireburdluvr85

Found the problem, the pins in the aldl were loose. I hate threads that never post an answer or drop off so I figured I'd help out the next guy with the cause. Thanks for the ones who helped!