OK, heres the rundown.

The car is a 95 LT1 that was an M6. I converted to a 4l60E and swapped to an A4 harness which turned out to be a 96-97. Car would turn over fine, but would not start. I got a continuous "No response from PCM" via Tuner cat ( _EE Def file) using my laptop and USB style adapter which previously worked with the M6 setup. When I turn the ignition to start, It turned over and I just get a soft slick from the area of the ABS. No fans or fuel pump.. nothin..

I also get the Same Tuner cat error using my stand alone bench top tuning harness.

I thought there may have been an issue with the harness so I picked up a 95 specific harness from this site. A few plugs (MAF and VSS) were different , but I addressed that.

Now, the car will NOT turn over, and I still get the "No response from PCM", and same soft click from the area of the ABS.

Picked up a new to me PCM from another 95 LT1 and before I installed it , I tried to test it on the bench top tuning harness. "No reponse from PCM". Car still acts the same..Doesnt turn over and the same soft click.

The car will turn over just fine if I jump the power wire to the starter.

Need some help here guys, As I am getting frustrated.

Thanks

 

you have to go thou the pin outs i did a 93 to 94 pcm and everything pluged in fine but there are a few diff pin outs you have to change

 

+1 to verifying pin outs. Are you sure the OBD2 harness will work on the OBD1 PCM..? Looks like your PCM is not running if fuel pump does not run 2 seconds after ign off-to-on sequence.

 

The harness is currently from a 95, and the PCM is from a 95 so the pinouts should be in the correct slots. Thats why I switched out the 96-97 harness, in an attempt to avoid changing pin outs.

Is there any way to tell for sure if the PCM's are dead. It wont respond when hooked to the car , or a bench top harness.

THanks

 

i double checked the pinouts at the PCM and they are all where they should be. I will start doing to testing of the pins for ground and power to see where I'm at.

Any other suggestions or things I should be looking for?

Thanks again

 

I was just re-reading the posts.. Is the starter still not cranking at all. Cranking should not have anything to do with the PCM. see this schematic ref shoebox http://shbox.com/1/starter_charging_95.jpg the theft deterrent relay (TDR) is picked by ground from the theft deterrent module (TDM) , security lite s/b on for 5 seconds after ign on then go off it all is OK and +12 from the neutral park switch (A4), I assume you added this switch during the conversion. From then on it's a straight circuit from ign switch thru the TDR to starter solenoid.

 

Its still not cranking at all. It was with the 96-97 harness and not with the 95 harness. Both PCM's are still tuned for the M6 , and the clutch switch has been bypassed.

If I jump to the starter wire , it will turn over. Could the theft deterrent relay cause this no crank condition?

Also, any ideas why the PCM's wont respond on the bench top tuning harness?

Thanks for the replies on this.

 

1- The TDR blocks +12V from getting to the starter solenoid, jumper around it see what happens. To pick the TDR the A4 has a PN switch and the M6 a clutch switch, do they use the same harness connector ? or are they different, do you have a the PN switch hooked up OK in the A4 shift linkage in center hump. I never messed around that area so I'm not sure how they do it.
2- Is you benchtop harness set up as follows : +12V BAT to B15 & B31 , +12V IGN to B30 and D3 , ground to B6 and D1 , read serial data D30 (read between D30 & ground).
NOTE*** some people have said that serial data is wired to pin D29 on ODB1 PCM's, you would have to look at your harness and see where the TAN wire goes to 29 or 30 ref this post : http://www.monodax.com/forums/tunerc...m-pinouts.html
3- CAUTION... On OBD2 PCM's +12V BAT must be on prior to activating +12V IGN or it may blow the PCM. Should be OK on OBD1 they say.
ref this page for above PCM info: http://www.gmassie.net/13secss/pcm_harness.html

 

First of all , Thank you bobdec and others for all of the help. I would love to say I figured it out but I havent confirmed a solution yet.

This is the update. I removed the entire harness , inspected everything and reinstalled. Installed the PCM and turned the Ignition to the "on" position, and the fuel pump primed and all seems well. I tapped it to start and it cranked. SOOO, thats a big improvement and tells me i missed something prior. Unfortunately, I cant try to start the car in the garage because the baby is sleeping, and its pouring outside so no go tonight... GRRRR.

I will try it first thing tomorrow to see if she fires up.

I did try to scan it again with TC and it still says "no reponse from PCM". If it fires up tomorrow i will address that issue, but will be happy.

Also, I double checked my bench top harness and there is no PCM ground in D6. Everything else is as prescribed in the schematic. Would this cause a prob?

Thanks again for the help on this.

 

Car Fired right up...

Now I gotta figure out why I cant access the PCM.

Thanks again guys!

 

Was previous post a mistype s/b ground to B6 and D1 in bench harness, NOT D6 ....

 

yea, thats was my fault. I also figured out my issue with the Tunercat. My driver was corrupt and not allowing the COMM port to relay info. I'm not a computer guy and my wife figured it out.

Thanks again for the help on this