[Jessners21]

I have a 2002 TJ that will not start. Battery was bad when I got it I replaced it but after it would not start. It cranks but no spark. In my root causing I have replaced the coil pack (2 were defiantly bad), replaced camshaft sensor. Adding gas to intake gives nothing so I didn't think fuel pump issue. However it doesn't seem that the pump is running (don't hear it). So I wanted to see if I got any codes off it and borrowed an OBD but if failed to read anything at all. Failure to connect. Tried in on my other 2002 TJ and worked fine so not the OBD unit.

So my thought is PCM is bad, which is why it isn't getting power where it is needed to start. (coil pack and fuel pump). However I was also thinking it could be wiring/connector gone bad. I am unsure though how to test if the PCM is really the cause before I drop more money on something I don't need, on a Jeep I never intended to keep.

For ref I bought 2 at one time as seller was only doing it as a package. I intend to fix and keep one and the other one was to do a little work and sell to put money towards the TJ I kept. Both are the same model but the PCMs are not the same so I don't think I can swap and run the OBD test on the other Jeep. Working TJ is 56044477AD and non-working TJ is 56041945AF.

Any help on how to test a PCM or wiring to figure out which is the problem would be appreciated.

 

[Digger84]

check for spark like this

 

[roaniecowpony]

I've been going through this on my JL. One of the guys on another forum is a professional automotive electrician and led me through a series of tests to narrow it down to the PCM. You'll need the pin assignments for the PCM connectors.

 

[Digger84]

8W-80 CONNECTOR PIN-OUTS
TJ
POWERTRAIN CONTROL MODULE C1 - BLACK 32 WAY
CAV
CIRCUIT
FUNCTION
A1--K18 18RD/YL (4.0L)
IGNITION COIL NO. 3 DRIVER
A2--F15 18DB FUSED IGNITION SWITCH OUTPUT (RUN-START)
A3--
A4--K4 18BK/LB SENSOR GROUND
A5--
A6--T41 18BR/LB PARK/NEUTRAL POSITION SWITCH SENSE
A7--K19 18GY IGNITION COIL NO. 1 DRIVER
A8--K24 18GY/BK CRANKSHAFT POSITION SENSOR SIGNAL
A9--
A10--K60 18YL/BK IDLE AIR CONTROL NO. 2 DRIVER
A11--K40 18BR/WT IDLE AIR CONTROL NO. 3 DRIVER
A12--K10 18DB/BR (2.5L)POWER STEERING PRESSURE SWITCH SENSE
A13--
A14--
A15--K21 18BK/RD INTAKE AIR TEMPERATURE SENSOR SIGNAL
A16--K2 18TN/BK ENGINE COOLANT TEMPERATURE SENSOR SIGNAL
A17--K7 18OR 5V SUPPLY
A18--K44 18TN/YL CAMSHAFT POSITION SENSOR SIGNAL
A19--K39 18GY/RD IDLE AIR CONTROL NO. 1 DRIVER
A20--K59 18VT/BK IDLE AIR CONTROL NO. 4 DRIVER
A21--
A22--A4 14RD/WT FUSED B(+)
A23--K22 18OR/DB THROTTLE POSITION SENSOR SIGNAL
A24--K41 18BK/DG OXYGEN SENSOR 1/1 SIGNAL
A25--K141 18TN/WT OXYGEN SENSOR 1/2 SIGNAL
A26--K241 18LG/RD (4.0L CALIFORNIA)OXYGEN SENSOR 2/1 SIGNAL
A27--K1 18DG/RD MANIFOLD ABSOLUTE PRESSURE SENSOR SIGNAL
A28--
A2--K341 18TN (4.0L CALIFORNIA)OXYGEN SENSOR 2/2 SIGNAL
A30--
A31--Z12 14BK/TN GROUND
A32--Z12 14BK/TN GROUND

CAV
CIRCUIT
FUNCTION
B1--
B2--
B3--
B4--K11 18WT/DB FUEL INJECTOR NO. 1 DRIVER
B5--K13 18YL/WT FUEL INJECTOR NO. 3 DRIVER
B6--K38 18GY (4.0L)FUEL INJECTOR NO. 5 DRIVER
B7--
B8--
B9--K17 18DB/TN (4.0L)IGNITION COIL NO. 2 DRIVER
B10--K20 18DG GENERATOR FIELD
B11--T23 18OR/LG TRANSMISSION LOW/OVERDRIVE SOLENOID
B12--K16 18LG/BK (4.0L)FUEL INJECTOR NO. 6 DRIVER
B15--K12 18TN FUEL INJECTOR NO. 2 DRIVER
B14--
B13--
B16--K14 18LB/BR FUEL INJECTOR NO. 4 DRIVER
B17--
B18-
B19--
B20--
B21--
B22--
B23--G60 18GY/YL ENGINE OIL PRESSURE SENSOR SIGNAL
B24--
B25--
B26--
B27--G7 18WT/OR VEHICLE SPEED SENSOR SIGNAL
B28--
B29--
B30--
B3--K6 18VT/OR 5V SUPPLY
B32-

CAV--CIRCUIT FUNCTION
C1--C13 18DB/OR A/C COMPRESSOR CLUTCH RELAY CONTROL
C2--
C3--K51 18DB/YL AUTOMATIC SHUT DOWN RELAY CONTROL
C4--V36 18TN/RD (SPEED CONTROL)SPEED CONTROL VACUUM SOLENOID CONTROL
C5--V35 18LG/RD (SPEED CONTROL)SPEED CONTROL VENT SOLENOID CONTROL
C6--
C7--
C8--K99 18BR/OR (4.0L CALIFORNIA)OXYGEN SENSOR UPSTREAM CONTROL
C9--K512 18RD/YL (4.0L CALIFORNIA)OXYGEN SENSOR DOWNSTREAM HEATER RELAY
CONTROL
C10--K106 18WT/DG (DRL)LEAK DETECTION PUMP SOLENOID CONTROL
C11--V32 18YL/RD (SPEED CONTROL)SPEED CONTROL ON/OFF SWITCH SENSE
C12--A142 14DG/PK AUTOMATIC SHUT DOWN RELAY OUTPUT
C13--
C14--K107 18ORLEAK DETECTION PUMP SWITCH SENSE
C15--K118 18PK/YL BATTERY TEMPERATURE SENSOR SIGNAL
C16--K299 18BR/WT OXYGEN SENSOR UPSTREAM CONTROL
C17--
C18--
C19--K31 18BR FUEL PUMP RELAY CONTROL
C20K52 18PK/BKEVAP/PURGE SOLENOID CONTROL
C21--
C22--C21 18DB/OR A/C SWITCH SENSE
C23--C90 18LG A/C SELECT INPUT
C24--K29 18WT/PK BRAKE LAMP SWITCH SENSE
C25--K125 18WT/DB GENERATOR SOURCE
C26--K226 18DB/LG FUEL LEVEL SENSOR SIGNAL
C27--D21 18PK SCI TRANSMIT
C28--
C29--D32 18LG SCI RECEIVE
C30--D25 18VT/YL PCI BUS
C31--
C32--V37 18RD/LG (SPEED CONTROL)SPEED CONTROL SWITCH SIGNAL

 

[roaniecowpony]

This was the source of these pages
STICKY - Jeep Wrangler TJ Factory Service Manuals (FSM) & Technical Documentation | Jeep Wrangler TJ Forum

 

[roaniecowpony]

I'm just going to give you some things I was told to check by an expert. I'm not the expert. Here's part of what I was told to check to ensure PCM communication. But where I get lost is where you could measure the bus signal. So, here's what I can give you to get started.

Disconnect the PCM connectors. Put the ignition to ON. Check the following pins in the connectors.

Check A2 Fused Ign Sw Out for 12v with your multimeter set to DC volts, one lead grounded and the other in the pin.
Check A22 Fused B (+) for 12v
Check A31 and A32 grounds with your multimeter set on ohms and one lead grounded and the other in the pin.
Check A4 for ground as well

After this, you need a real expert.

 

[MrSig]

and enjoy the forum!

 

[Jessners21]

View attachment 4613309


8W-80 CONNECTOR PIN-OUTS
TJ
POWERTRAIN CONTROL MODULE C1 - BLACK 32 WAY
CAV
CIRCUIT
FUNCTION
A1--K18 18RD/YL (4.0L)
IGNITION COIL NO. 3 DRIVER
A2--F15 18DB FUSED IGNITION SWITCH OUTPUT (RUN-START)
A3--
A4--K4 18BK/LB SENSOR GROUND
A5--
A6--T41 18BR/LB PARK/NEUTRAL POSITION SWITCH SENSE
A7--K19 18GY IGNITION COIL NO. 1 DRIVER
A8--K24 18GY/BK CRANKSHAFT POSITION SENSOR SIGNAL
A9--
A10--K60 18YL/BK IDLE AIR CONTROL NO. 2 DRIVER
A11--K40 18BR/WT IDLE AIR CONTROL NO. 3 DRIVER
A12--K10 18DB/BR (2.5L)POWER STEERING PRESSURE SWITCH SENSE
A13--
A14--
A15--K21 18BK/RD INTAKE AIR TEMPERATURE SENSOR SIGNAL
A16--K2 18TN/BK ENGINE COOLANT TEMPERATURE SENSOR SIGNAL
A17--K7 18OR 5V SUPPLY
A18--K44 18TN/YL CAMSHAFT POSITION SENSOR SIGNAL
A19--K39 18GY/RD IDLE AIR CONTROL NO. 1 DRIVER
A20--K59 18VT/BK IDLE AIR CONTROL NO. 4 DRIVER
A21--
A22--A4 14RD/WT FUSED B(+)
A23--K22 18OR/DB THROTTLE POSITION SENSOR SIGNAL
A24--K41 18BK/DG OXYGEN SENSOR 1/1 SIGNAL
A25--K141 18TN/WT OXYGEN SENSOR 1/2 SIGNAL
A26--K241 18LG/RD (4.0L CALIFORNIA)OXYGEN SENSOR 2/1 SIGNAL
A27--K1 18DG/RD MANIFOLD ABSOLUTE PRESSURE SENSOR SIGNAL
A28--
A2--K341 18TN (4.0L CALIFORNIA)OXYGEN SENSOR 2/2 SIGNAL
A30--
A31--Z12 14BK/TN GROUND
A32--Z12 14BK/TN GROUND

CAV
CIRCUIT
FUNCTION
B1--
B2--
B3--
B4--K11 18WT/DB FUEL INJECTOR NO. 1 DRIVER
B5--K13 18YL/WT FUEL INJECTOR NO. 3 DRIVER
B6--K38 18GY (4.0L)FUEL INJECTOR NO. 5 DRIVER
B7--
B8--
B9--K17 18DB/TN (4.0L)IGNITION COIL NO. 2 DRIVER
B10--K20 18DG GENERATOR FIELD
B11--T23 18OR/LG TRANSMISSION LOW/OVERDRIVE SOLENOID
B12--K16 18LG/BK (4.0L)FUEL INJECTOR NO. 6 DRIVER
B15--K12 18TN FUEL INJECTOR NO. 2 DRIVER
B14--
B13--
B16--K14 18LB/BR FUEL INJECTOR NO. 4 DRIVER
B17--
B18-
B19--
B20--
B21--
B22--
B23--G60 18GY/YL ENGINE OIL PRESSURE SENSOR SIGNAL
B24--
B25--
B26--
B27--G7 18WT/OR VEHICLE SPEED SENSOR SIGNAL
B28--
B29--
B30--
B3--K6 18VT/OR 5V SUPPLY
B32-

CAV--CIRCUIT FUNCTION
C1--C13 18DB/OR A/C COMPRESSOR CLUTCH RELAY CONTROL
C2--
C3--K51 18DB/YL AUTOMATIC SHUT DOWN RELAY CONTROL
C4--V36 18TN/RD (SPEED CONTROL)SPEED CONTROL VACUUM SOLENOID CONTROL
C5--V35 18LG/RD (SPEED CONTROL)SPEED CONTROL VENT SOLENOID CONTROL
C6--
C7--
C8--K99 18BR/OR (4.0L CALIFORNIA)OXYGEN SENSOR UPSTREAM CONTROL
C9--K512 18RD/YL (4.0L CALIFORNIA)OXYGEN SENSOR DOWNSTREAM HEATER RELAY
CONTROL
C10--K106 18WT/DG (DRL)LEAK DETECTION PUMP SOLENOID CONTROL
C11--V32 18YL/RD (SPEED CONTROL)SPEED CONTROL ON/OFF SWITCH SENSE
C12--A142 14DG/PK AUTOMATIC SHUT DOWN RELAY OUTPUT
C13--
C14--K107 18ORLEAK DETECTION PUMP SWITCH SENSE
C15--K118 18PK/YL BATTERY TEMPERATURE SENSOR SIGNAL
C16--K299 18BR/WT OXYGEN SENSOR UPSTREAM CONTROL
C17--
C18--
C19--K31 18BR FUEL PUMP RELAY CONTROL
C20K52 18PK/BKEVAP/PURGE SOLENOID CONTROL
C21--
C22--C21 18DB/OR A/C SWITCH SENSE
C23--C90 18LG A/C SELECT INPUT
C24--K29 18WT/PK BRAKE LAMP SWITCH SENSE
C25--K125 18WT/DB GENERATOR SOURCE
C26--K226 18DB/LG FUEL LEVEL SENSOR SIGNAL
C27--D21 18PK SCI TRANSMIT
C28--
C29--D32 18LG SCI RECEIVE
C30--D25 18VT/YL PCI BUS
C31--
C32--V37 18RD/LG (SPEED CONTROL)SPEED CONTROL SWITCH SIGNAL

This is awesome thank you. Off to see what I find.

 

[Jessners21]

This was the source of these pages
STICKY - Jeep Wrangler TJ Factory Service Manuals (FSM) & Technical Documentation | Jeep Wrangler TJ Forum

View attachment 4613310 View attachment 4613311

Thank you! I was searching for something like this and couldn't find it yet.

 

[roaniecowpony]

Thank you! I was searching for something like this and couldn't find it yet.

That pinout chart was taken out of the 2002 manual on that site linked. It seems to differ from what Digger posted.

 

[Jessners21]

Well my A22 has no voltage. Pro, my PCM is not bad it just has no power, con now I am on a search for where the power loss is coming from.

Found a wire schematic and it shows the battery basically breaks off to stop lights, PCM, shut down relay, and fuel pump relay. This would explain the fuel pump not kicking on. However the break lights work. So I guess the break is somewhere in between break lights and pcm.

Currently searching for a harness routing diagram to figure out where I need to look.

 

[roaniecowpony]

Looks like A22 is fed by fuse 9 in the main fuse panel

 

[Digger84]

This actually shows pin A22

try this
battery thru fuse 9 in PDC to pin A22 on PCM
right click image and open in new tab for larger view

 

[RUBI 4 MY MRS]

If you have no 12v power to a22 & IF fuse 9 checks good with a meter there is a good chance there the red/white wire that connects fuse 9 to PCM a22 is bad. Here is a link to someone who had this happen. It was a bit different symptoms but same wire was corroded almost through (yours might be completely separated) where the harness passes near the battery & is a known place where harness damage happens if battery acid penetrates the harness wrapping.

The discovery is at post 14.

https://www.wranglerforum.com/threads/dreaded-asd-relay-chattering.2467495/

Notice in the diagram digger posted that fuse 9 also powers the ASD relay so be sure the ASD is getting 12v just in case the splice point at the fuse is bad which will can kill power to both relay & PCM. Splice circled in red & located in the underside of the PDC.

 

[Jessners21]

So thanks for everyone's help. Thought I would share the final results. I found that I had 12V at fuse, 0V at PCM and 0 Volts at C103 connection. So I worked my way through the harness checking for the loss. It happened to be in the harness about 12in from the fuse panel.

I have never seen something like what I found and neither has my dad who worked on cars his whole life before retiring. The wire has no outside damage but was all bloated. I cut it open to find the wire completed gone and only corrosion. I had to remove about 1.5 feet of wire to find good wire and spliced in a new section.

I have spark now but timing it off and it backfires so onwards to new I guess.

 

[roaniecowpony]

Congratulations!!!

You should do a crank/cam position sensor relearn.

 

[RUBI 4 MY MRS]

Good find & thanks for posting findings & also the photos. I am seeing this more frequently as these TJs age. That bubbling insulation is a definite tell-tale that battery acid has found its way there.

 

[Jerry Bransford]

Nice job finding that problem!!!

 

[Digger84]

relearn not really an issue on a 2002

looking at photo my guess is wire/insulation got crushed (probably under something that was tightened down probably fairly long ago, maybe even dating back to when it was originally assembled) which led to insulation damage then water entry and over time corrosion of conductor strands inside insulation, but no matter as it is now fixed