Originally Posted by
Neukam
If EGR is commanded, The PCM might make fuel and spark corrections to compensate for the EGR flow that it expects, even if the system is physically or electrically disabled. By setting the enable parameters to impossible or implausible values, we prevent EGR from ever being commanded.
When the AIR system is commanded, the PCM may increase IAC in anticipation of the additional load. You probably wouldn't ever notice, but if it's not there we should disable it. It's best not to lie to the computer unless you have to.
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Looking at another bin that I believe to be stock, 77 is disabled and 78 is enabled. There should be no problem with leaving both disabled, but enabling them can make troubleshooting easier if there's ever a problem. I'm not sure if those error codes would set a MIL, but they would be available to see on the scanner.
I recommend wiring as per the lower half of the diagram.
In the upper half of the diagram, the PCM will energize relay 1, causing fan 1 to run at full speed. If necessary, it will energize relay 2, turning on the second fan at full speed in addition to the first. This strategy works, but you will get more noise and you won't get even airflow across the radiator and condenser in the primary cooling mode.
In the lower half of the diagram, the PCM first energizes relay 1, supplying positive power to the left fan. The left fan negative runs through the deenergized relay 3 and through the right fan positive, thus putting both fans in series and both fans running at reduced speed, noise, and electrical load. The negative of the right fan is always grounded. If necessary, The PCM will activate the secondary output which energized relays 2 and 3. Relay 2 will supply 12v power to the right cooling fan causing it to run at full speed. Relay 3 will divert the negative of the left fan (which was previously connected to the positive of the right fan) to ground, causing it to also run at full speed.
To summarize the lower half of the diagram
- Primary output energized - relay 1 energized - fans in series running at reduced speed
- Primary and secondary outputs energized - relays 1,2, and 3 energized - both fans running in parallel at full speed
- Secondary output energized without primary output (this is a failure mode) - right fan runs at full speed, left fan does not run
A lot of effort goes into doing swaps like these properly. There's a lot to learn and a lot of details to work through. Be proud that you have stuck with it and committed to finishing it. Many people don't and abandon their projects. Give yourself a pat on the back.
Ideally, you would wire the A/C to mimic the donor vehicle, including the pressure sensor on the high pressure line. This would allow proper IAC compensation with A/C engagement, wide open throttle cutout, and proper fan control based on system demand.
Technically, either way should work, but the lower half would be ideal. According to RockAuto's catalog, OE thermostat is 180F. I can neither confirm, nor deny.
The XDF is what TunerPro uses to interpret the binary data in the bin. If the XDF file loaded into TunerPro doesn't match the bin that's being edited, or if it is just plain wrong, you will see incorrect values. What you were seeing, did not match what I was seeing. That is why I mentioned the XDF possibly being incorrect. The XDF that I linked to seems to be correct and, for all practical purposes, complete. You are unlikely to find an XDF that's totally complete, but many tables and values that are missing from the XDF just don't need to be changed...ever.
I believed that I understood your VSS sensor setup, and your response to stew86MCSS396 has confirmed it. The PCM reads the VSS input from the sensor you installed in the back of the trans housing. This tells the PCM the transmission output shaft speed. The PCM then converts the output shaft speed to vehicle speed, compensating for gear ratio and tire size. This vehicle speed data is used for many things, including idle control, speed limiter, and transmission control. Error 72 corresponds to this sensor input. The PCM also has a VSS output that sends a 4000 pulse per mile signal (calculated from the VSS input) to other devices in the vehicle like the electronic speedometer, cruise control module, ABS, radio, outside temperature display, etc. The other devices have a pullup resistor that pulls the voltage on the PCM's output high. When the PCM pulses it's output, it pulls the voltage low. When the PCM is not outputting a signal, it monitors it's output to verify that it's being pulled high by another device. In this way it can detect if it's output is open or shorted to ground. Error 97 corresponds to this diagnostic routine on the PCM's VSS output. If you don't have another device connected to the PCM's VSS output, the output will never be pulled high, and the PCM will set error 97. Disabling Error 97 shouldn't actually affect the output, only the diagnostic routine. You can disable it and when you connect your cruise control module you can decide if you want to reenable it.
Despite being number 4 on my list, this should be your first priority.
Some parameters in some XDFs have comments. If you mouse over a parameter in the parameter tree, you will momentarily see a comment pop up if that parameter has one. Not all parameters have comments, and they are specific to (and inherited from) the XDF. If you select View>Parameter Comments, a Parameter Comments window will appear. This will show the comment for the active parameter that you have double clicked and opened. In the XDF that I linked, under CCP Enable - Min Coolant Temp there is the following comment
I don't know the details of how this particular PCM handles BLM. With that in mind, I'd prefer to trust the GM Engineers. Those guys are smarter than me. I don't see any harm in connecting the system if it's not too much trouble. It will have a minimal effect on air/fuel ratio (and the PCM will compensate for it) and it will keep some hydrocarbons out of the atmosphere. If you have all the components and can hook it back up easily, I would do so. If not, you can disable the code and monitor BLMs to make sure you don't get any undesirable behavior.
I don't know if I'm a wise man, although I've often been called a wisea--
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