When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I see lots of posts in here about the stepper motors going bad and how to replace them.
But has anyone been able to successfully bench test them?
All the wiring harnesses and forum posts I can find related to bench testing all seem be fore the GM/Chevy Trucks.
I guess our IPCs arent GMT800 based, and the trucks are. Which seem to be the more popular topic when searching google.
Anyone here got a harness or wiring diagram bench testing the monte carlo/impala IPC?
Only bench test I have done is a power on, but that is a minimal test. Having a way to fully bench test would be cool, but I never pursued it as I don't tinker much with clusters. But if you find something, I am definitely curious.
So I am currently using PCM Hammer, Tuner Pro, and Universal Patcher for most of my tinkering.
But theres a user that has created a Plug-in for PCM Hammer called IPC Hammer.
And it is specifically for GMT800 Clusters. Which I think are found in the Silverado's from 2000-2005.
But I cant find any info on the Monte Carlos from the same era so I don't know if they're based on the same GMT800 infrastructure or not.
If they are the same, in theory I could do all the Tech2 Tests, Gauge sweeps, Mileage adjustments, Gauge enable/disable (Boost/Oil Pressure/Bat Voltage) for swapped clusters.
It looks like a very intuitive program.
I did learn that our clusters use Class2 Serial. (SAE 1850) same as our PCMS. So in theory I should be able to tie it into the PCM Bench harness and do some more testing.
Do you mind me asking which Pins you used to do the power up test?
Far as I can tell, I think I need the following: Could you confirm?
A1 -(Battery)12v
A2 -Ground
A4 - Ground
A8-(Ignition) 12v
B1-(Lamp Positive) 12v
Thanks In Advance
Edit:
Attempted a bench test last night. These are the correct pins for basic power on and lamp test. If you'd like to test the turn signals you'll need a couple other pins.
I also tied into pin A7 which is Class 2 Serial data, and I was able to communicate with the cluster using a Tech2Tool and Pin2 on the OBD connector.
I could do all the lamp tests and Gauge sweep tests using the GM software.
Last edited by Henderson21; May 25, 2025 at 09:58 AM.
So I built a PCM bench harness for flashing PCMs. I just followed this information and it works perfectly.
This would have been handy in the other thread I had asking about PCM bench testing. Lol.
I did a follow up post explaining this diagram.
It's the same as the LS1 PCM harness.
That being said, if your interested in bench testing gauge clusters. Check out the pin out above your post in this thread.