danhr

iTrader: (18)

Ok, engine and wiring harness are from a 2000 z28. The car drives and runs fine. The factory tach, fuel gauge, or coolant temp gauge do not work. they give a little nudge when I turn the ignition on, but that's about it. My huge ricer tach works though (it's getting it's signal directly off of the pcm).

Here's where it gets funky.

Fans operate normally (they kick on after the car has been ran for a bit, and then cut off, so I assume they are getting signal).

I hook a tech2 up to it, the tech2 gets power (cig. lighter works), but says it can not communicate with the vehicle.

I'm thinking a bad pcm, so I swap for another pcm... and still the same thing!

and yes i've already checked all the fuses

anyone have any ideas before I set my car ablaze?

jmilz28

iTrader: (13)

Try a fresh battery first.
Then check for corroded battery cables.
Then check your grounds.
80%+ it's one of those.

01WS6/tamu

iTrader: (37)

After checking to make sure all of the grounds are clean and tight and the battery is hot. Disconnect all modules off of the data bus, bcm, ipc, sdm, pcm. Then check the bus for a short to power or ground. Then go to the pcm class 2 databus pin at the pcm and use a DVOM set on diode check or ohms and hook one end up at the dlc and the other at the pcm connector. The meter should emit a steady beep, or show resistance if your meter does not have diode check function. If it does not do any of the above then there is an open circuit in the class 2 communications circuit. The IPC uses class 2 databused signals for many of the lamps and gauges. The ones you described not functioning are the ones that are databussed.

jmilz28

iTrader: (13)

I think this covers most of the remaining 20%.

Formula413

iTrader: (1)

Holy crap, I was able to follow about two sentences of that before my brain started to overheat.

danhr

iTrader: (18)

could you break some of that down barney style. pretty much the only thing i understand in that is continuity and pcm and bcm

what's the databus, i'm assuming it's one of the two main connectors coming off of the pcm?
ipc?
sdm?
whats the class 2 databus?


edit, i checked/cleaned all grounds, and hooked the car up to a fully charged battery pack, and am running the tech2 directly from the cigarette lighter as a power source (which does work)

01WS6/tamu

iTrader: (37)

Class 2 is basically the communication protocol. The modules instrument panel cluster, powertrain control module, body control module, sensor diagnostic module(airbag) communicate signals over the databus. DLC is the datalink connector under the dash. The bus is essentially a single wire that runs to each of the modules to allow them to talk and are all joined using a factory splicepack and then t'd into the DLC to allow for diagnostics.. If you are familar with network systems it is set up like a token ring system. When all of the modules are disconnected this bus should not have any active signals on it IE power ground or other induced resistance. IF any of the above are present it kills databus communications IE the modules cannot talk and you have the situation with your gauges. Since you have a tech 2 try to establish communication with the bcm, ipc, and sdm and report back. If you cannot talk to any of these modules then it is more than likely a bus problem. If not it may simply be a connection issue from the splicepack to the pcm.

SSmokinz

iTrader: (5)

Any luck fixing this problem yet?

danhr

iTrader: (18)

Yes! The star connector by the aldl port under the dash needed to be cleaned. There was no continuity across it. I pull it out, clean it, put it back in and voila.

dnj

I have installed the LS1 drivetrian and wiring harness from a 2000 camaro in my 66 chev pickup. I have deleted my airbag stystem and VSS, had the PCM reprogramed by Street and Performance, but guages not working, only jump slightly when I turn on the ignition. How can I determine whick in put is missing from the serial 2 data?

Thanks! DnJ