So I bought a 97XJ with no engine but it used to be a 2.5TD.
I'm going for an LS swap (Novak) so I only need the PCM to be the mule to feed the instrument cluster. Problem is the PCM is not sending anything to the IC and I can't communicate with it on OBD (SCI).
2 questions: how to confirm the PCM is dead, and if it's dead can I replace with a 4.0 PCM just to feed the cluster?
1; Is PCM dead
Here is what I know and did
- CCD bus is alive and well. 60 ohms. proper comm to SKIF, airbag, IC, no issues there.
- IC is good, auto test with the button or OBD works fine.
- Tested the PCM in the car and on the bench
- All sensors disconnected (i'm removing all the diesel things to keep only oil pressure, ECT, vss, fuel level.
- 5v output is ok
- SCI Receive is giving me 4.5v (should be 5v with pull-up resistor?) I can scope pulses from OBD machine on SCI receive.
- SCI transmit floating until I plug OBD, then gets 5v from OBD. No pulse back on SCI tx although some very small (0.05v) pulse can sort of be seen. Maybe crosstalk from RX line.
- Opened the PCM box (it's those old ones like the 91-95 XJ - weird diesel configuration)
- could not see any obvious damage on solders, but the 16534 flash memory has been replaced (probably immo delete)
Those 2.5Td ran a Jeep PCM and a Bosch ECU (MSA controller). The PCM handles only cluster communication and generator field while MSA handles all engine management. But those 2 units are connected together trough SCI and a mysterious "Engine Disable signal" wire, Tachometer wire and FLT (Fault?) wire. Not sure if there is some weird interaction here.
Anyone has any good idea to further confirm/test if PCM is bad?
2: IF PCM is bad, can I replace with any working 4.0l PCM?
I just need it to read sensors (VSS, fuel level, engine coolant temp, oil pressure, tach from Novak emulator) and send to IC.
Can I just get any 97 PCM? Will I get problems with not plugging it fully? Issues with SKIF?
I'm going for an LS swap (Novak) so I only need the PCM to be the mule to feed the instrument cluster. Problem is the PCM is not sending anything to the IC and I can't communicate with it on OBD (SCI).
2 questions: how to confirm the PCM is dead, and if it's dead can I replace with a 4.0 PCM just to feed the cluster?
1; Is PCM dead
Here is what I know and did
- CCD bus is alive and well. 60 ohms. proper comm to SKIF, airbag, IC, no issues there.
- IC is good, auto test with the button or OBD works fine.
- Tested the PCM in the car and on the bench
- All sensors disconnected (i'm removing all the diesel things to keep only oil pressure, ECT, vss, fuel level.
- 5v output is ok
- SCI Receive is giving me 4.5v (should be 5v with pull-up resistor?) I can scope pulses from OBD machine on SCI receive.
- SCI transmit floating until I plug OBD, then gets 5v from OBD. No pulse back on SCI tx although some very small (0.05v) pulse can sort of be seen. Maybe crosstalk from RX line.
- Opened the PCM box (it's those old ones like the 91-95 XJ - weird diesel configuration)
- could not see any obvious damage on solders, but the 16534 flash memory has been replaced (probably immo delete)
Those 2.5Td ran a Jeep PCM and a Bosch ECU (MSA controller). The PCM handles only cluster communication and generator field while MSA handles all engine management. But those 2 units are connected together trough SCI and a mysterious "Engine Disable signal" wire, Tachometer wire and FLT (Fault?) wire. Not sure if there is some weird interaction here.
Anyone has any good idea to further confirm/test if PCM is bad?
2: IF PCM is bad, can I replace with any working 4.0l PCM?
I just need it to read sensors (VSS, fuel level, engine coolant temp, oil pressure, tach from Novak emulator) and send to IC.
Can I just get any 97 PCM? Will I get problems with not plugging it fully? Issues with SKIF?
