PCM diagnostics?
Thread Starter
Staging Lane
Joined: Jul 2004
Posts: 52
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PCM diagnostics? I have an LT1 that I've swapped into a Datsun 240Z. I've removed all the emissions equipment (EGR, vapor canister, Air pump, CATS), the A/C, Powersteering and have it mated to a T5 tranny. This means the all the electronics for these items have been disconnected from the PCM. The engine and PCM came from a 1995 Caprice 9C1 cop car which had dual cooling fans and an auto tranny. I took the underhood fusebox from the Caprice and have wired up a Taurus 2 speed fan through 3 relays to look like dual fans. The tach output from the PCM drives the stock Datsun tach which has been recalibrated to read correctly.
I'm having trouble getting the fan(s) to work correctly. When I start the engine it idles/runs great but after about 30 seconds the fan will kick on at low speed then switch to high speed and runs all the time. I've reprogrammed the computer to turn it on at 87C and 96C respectively. When I use EFILive to check the fan toggles they are both turned on even though the coolent temp is no where near hot enough. I've also looked at the A/C pressure and oil temp readings with DataMaster and they are negative values which is understandable as there is nothing hooked to those PCM circuits. I also found that several DTCs are being set for the TCC and some body control functions and a missing SES light. I haven't wired the SES light yet so that's understandable as well.
I have used TunerCat to turn off all the trouble codes for the non-existant emissions stuff and make some other small adjustments and I bought a mail order tune from PCMForLess.
All this to get to my questions:
1. Is the PCM going into some kind of limp-home mode?
2. How can I delete all the transmission related parameters?
3. How can I delete the body control function related parameters?
4. Is there a comprehensive source for what the voltage/current readings should be for all the parameters monitored by the PCM?
I understand this is really an LS1 site but I haven't been able to find an LT1 site with a similar level of technical knowledge, if one exists please point me in that direction.
One last thing, the 1995 LT1 is OBD1 compliant.
Thanks
ZcarGuy
I'm having trouble getting the fan(s) to work correctly. When I start the engine it idles/runs great but after about 30 seconds the fan will kick on at low speed then switch to high speed and runs all the time. I've reprogrammed the computer to turn it on at 87C and 96C respectively. When I use EFILive to check the fan toggles they are both turned on even though the coolent temp is no where near hot enough. I've also looked at the A/C pressure and oil temp readings with DataMaster and they are negative values which is understandable as there is nothing hooked to those PCM circuits. I also found that several DTCs are being set for the TCC and some body control functions and a missing SES light. I haven't wired the SES light yet so that's understandable as well.
I have used TunerCat to turn off all the trouble codes for the non-existant emissions stuff and make some other small adjustments and I bought a mail order tune from PCMForLess.
All this to get to my questions:
1. Is the PCM going into some kind of limp-home mode?
2. How can I delete all the transmission related parameters?
3. How can I delete the body control function related parameters?
4. Is there a comprehensive source for what the voltage/current readings should be for all the parameters monitored by the PCM?
I understand this is really an LS1 site but I haven't been able to find an LT1 site with a similar level of technical knowledge, if one exists please point me in that direction.
One last thing, the 1995 LT1 is OBD1 compliant.
Thanks
ZcarGuy
