I just had the dash apart and replaced the hvac door modules. now I don't have any dash lights or gauges working in the dash and the hvac dash controller is only displaying f/c noting else the engine, lights, cig lighters, all work cant pull any codes says I'm not connected.
Ive checked all the fuses under the hood ,dash, and rear seat all were good, so no easy fix there lol. the hvac programmer and the ip module along with the bcm are all on the same fuse which test out as good.
my question is how can I test these modules to see if they are bad? I was chasing a intermitting short which seemed to take me to the hvac system had the air mixing heat/ cold door module had a cracked gear .changed the three on the sides while I was in there, nasty job to do cant see or reach with any comfort.
I am going thru the web site to find out how to test these modules as they are expensive I want to be sure they are bad before throwing money at the problem thanks for any help I can get.

When I purchased a 2001 Lesabre Limited it was displaying f/c as well. The Dash Integration Module was burned out. I picked one up at a junkyard for 50 bucks.

If everything worked before you took the dash apart and now it doesn't, I would look for a wiring connection you missed or did not seat properly.

I am going to try the troubleshooting the "scanner can not connect", seems I need to unplug all the modules then with scanner checking for data reinstall one module at a time till I lose connection that will be the module that needs replacing. once I have the scanner collecting data I can see if I have any problems wish me luck. lol will report what I find
is the bcm the same as dash integration module? not getting a connection with the scanner troubleshooting will show which one is not allowing the connection which maybe the bad module.
as the hvac and the I/p an the bcm are all interconnected and all are costly I want to get the right one replaced

The DIM and BCM are 2 different modules.

Ive been busy. after unplugging the bcm, hvac programmer modules and the ipc I was able to connect for engine codes P1604, P1610 show up. With them reinstalled I get these codes P1604 and P1610. the climate controller only shows c/f , the ip cluster the lights work nothing else.
These I believe mean that there is no data connection between the pcm and the ip cluster and no data connection between pcm to the bcm? I have plugged and unplugged bunches of times checked soldered connections in climate controller and in the IP cluster, and still trying to find the DIM ? my eyes will fall out looking for answers and not being smart enough to find and ask the right questions to get answers so I can get everything working again lol

lets see I now have some more to go on lol.
I now have a few codes to add to this B 1159, B1163,U1255, P1604, P1610.
I have no scanner communication with the bcm branch in any setting or from the bcm, same no communication in the IPC branch, heating a/c branch. IPC is powered up has the lights nothing else no idiot lites when turn key on, climate control has only f/c displayed so has power will not do anything else lol. driving lights, turn/stop work, no interior lights work though.
It will take me a bit to look these all up and even longer to understand it, serial data communication, no vacuum hoses involved, I use to hate them this maybe worse lol. time to get the shop manual and see what it has to say about this and how to test it.
any help with this? I'm to old to learn anything new. lol I'm suppose to be retired dang it.

I have 12 volts on class2 network, I believe maybe an internal problem with one of the modules, from what I just read, so I will pull modules out of the system till I can lose the 12 volts on the DLC #2 pin I understand it should only have 0 to 7 volts for transferring data with 0 for no data being sent and it will fluctuate up to 7 volts? so 12 volts is a problem. I don't have a scope so I will try and get rid of the 12 volts a see if that fixes this problem of no communication with the scanner and get my dash and climate controls working again. But first breakfast I am hungry and this is driving me crazy lol