To verify proper procedure to disconnect TCM ans Reset PCM please check this and advise

Disconnect negative cable from battery
Disconnect positive cable from battery
Disconnect TCM
Ground positive and negative cables together for 10 seconds
turn on headlights to discharge any residual voltage
reconnect TCM?
reconnect positive battery cable
reconnect negative battery cable
plug in OBD2 adapter
turn key to run position (listen for fuel pump hum)
try to connect to PCM via Torque App

 

1. Disconnect battery negative and set aside
2. Disconnect TCM
3. Reconnect battery negative
4. Turn ignition to RUN (ON but not start/crank)
5. Test OBD2 connection with adapter (if connection works - celebrate - we are getting somewhere)

If OBD2 connection is still no-good:

6. Disconnect battery negative and set aside
7. Reconnect TCM
8. Reconnect battery negative
9. Turn ignition to RUN (ON but not start/crank)
10. Test OBD2 connection with adapter (if connection works - celebrate - we are getting somewhere)

Most of that reset nonsense is a myth perpetuated by the internet. It was posted on one of the aftermarket sites (like 4wd.com or quadratec, and had no details regarding which vehicles and years it even applied to - if any - as if all Jeeps of every kind over 30 years shared a common computer).

 

Put the celebration stuff away

no obd2 connection with TCM disconnected

no obd2 connection after reconnecting TCM

I noticed that after I reconnected the TCM and the battery, when turning the key to the on position I heard a click from the engine area. Turning the key off after obd2 connection failure and turning the key back to the on position did not recreate that click.

 

Next step will be to test that cavity at the PCM where it senses whether the ignition is on (energized by that A21 circuit we tested earlier). Because the behavior you have observed is still consistent with the PCM not knowing that the ignition is on. Meaning, the behavior you are seeing would be the same as if you had never turned the key to the ON/RUN position (no fuel pump prime, no obd2 connection, no asd activity). I'll post that PCM cavity as soon as I get back to my FSM at home.

 

Jump 30 and 87 in the fuel pump relay socket.

Many issues with PCMs are caused by broken solder joints (especially where the cables connect inside) and fried capacitors. These are easily repaired with moderate soldering skills. At some point you might want to at least take a look to see if that's the case.

 

This is from my minivan, but is a good example of the type of thing you'd be looking for:

 

I guess it isn't just us that fall apart with age...lol

 

PCM cavity A2 (connector C100) - Fused Ign Switch Output (RUN/START)

Btw, I assume you have checked all of the fuses in your power distribution center? Particularly Fuse 8 (60 amp)?

 

double,tripled checked all the fuses in the PDC and under the dash. Used Multi meter and touched both sides of each fuse.

so I am assuming that A2 is the second from the left on the bottom row?

Do I check the connector and or the cav on the PCM?

Do I do a volt test or a resistance/ohm test or continuity test?

Mechanics I am not so bad, electric is a bit foreign to me.

btw...thanks for the help, I really appreciate it.

 

Yes it is the connector with the black top (there are 3 connectors), it is 2nd from the left on the bottom row when looking into the connector with it unplugged. You can probably do this particular test with it unplugged. Many times with PCM cavity tests, you have to use a T-pin or special backprobe needle and test the pin from the back of the connector while it remains plugged in. But I think this pin should become energized even with the connector off of the PCM (because it basically comes from the ignition switch.)

You will test it for voltage just like you tested the other things. With the red probe on the pin in the connector, and the black probe on a known good ground. Just near the PCM, going towards the windshield on top of the inner fender, there is a ground connection location with a bolt/screw and a couple of wires connected to it. The top of that screw head should provide a good ground.

You should get no voltage on that pin until the ignition is turned to the RUN/ON position (no need to crank), then the pin should be energized to somewhere near battery voltage (approx 12v).

Be gentle with your PCM connectors. They don't get moved around that often.

 

In the instance of checking a wire from a PCM, it is acceptable practice to pierce the plastic wire coating with a safety pin, using that as your probe
(just seal the tiny hole with supeglue or even nail polish)

gently moving, connecting & disconnecting the PCM harness is also probably needed.

That would move you closer to ruling in/out a failed PCM

If you are feeling very tired, firing the parts canon on a replacement PCM would not be overly premature imo, seen blokes do it earlier than you, and resolve the problem

 

Removed black connector from PCM

Key on, voltage at A2, bottom row second from left...voltage 11.91 battery is at 12.36

 

We can't say definitively that the PCM is toast, but we are quickly approaching the point where it makes sense to try a known good PCM.

You did a lot of good tests. The last thing I would want to rule out before swapping the PCM is a general electrical connectivity problem of the PCM.

For example, testing to see if the PCM is providing voltage on any of its cavities at all (is there any evidence it is alive at all). Because being able to crank/start is one of the few things that doesn't care about the PCM. The ASD and Fuel Pump relays, and various obd2 sensors depend on the PCM, and all of them seem dead in the water. Next, is there perhaps a general grounding problem at the PCM. We should check at least one PCM cavity that is supposed to be providing ground to ensure that it actually is. If the PCM is not properly grounded, then it would not be able to provide ground on any of its cavities.

Have you inspected the ground connection that is located behind the oil dipstick tube bracket?

 

Based on the picture I posted earlier, it looks like cavity A4 on the PCM should be providing a ground we can test.

To test:

1. Multimeter in volts mode
2. Black meter probe on cavity A4 of PCM
3. Red meter probe on a known source of voltage (battery positive terminal, or something else that is constantly powered)
4. If voltage reads somewhere near battery voltage (approx 12v) then cavity A4 is providing ground.

 

I show A4 to be brown/yellow and "Sensor ground". This is the (-) going to the sensors.
The PCM grounds itself I show as A31 bk/tn and A32 bk/tn. These would go to the engine/battery/alt. grounds.
A22 red/white is the Fused B+ , A2 red/ light green is the fused ignition switch input.