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Bad suspension components with no Service light. WHY?

MP1155

New Member
Joined
Sep 22, 2018
Messages
3
Location
WI
2007 avalanche LTZ with Z55 . I have many questions and have been searching the forums. There are links to threads that lead to dead pages related to Z55/autoride, can someone provide a working link please - to one of the older articles that can teach me all i need to know? but...

Why would my service suspension light not come in in the DIC? I know components aren't working - the compressor doesn't come on, there are tears in the bags on the rear(fraying gone too far) and I even tried unplugging the individual shocks (only both rear, i could try the front, but im done for the night). Visual inspection has shown deteriorating components, but I am questioning the value of replacement if the computer isn't even working. I did check fuses. there is one larger 40 amp that i wasn't yet able to pull, but visually (through the clear top) it looks as good as the others.
 
If anyone is finding this, and was willing to help - don't worry, i think i've figured it out.

I have now found a very helpful youtube video, or a series of them, that in total, have provided a bit of direction and confidence.
First, i learned that simply unplugging the sensors may not trigger an event to signal the service suspension. ALso, a bad compressor does not signal service suspension, which means a blown air bag also would not signal a service suspension. I am confused as to why Driving with a loaded trailer and hitch nearly on the ground didn't signal a problem... but I imagine the electronics are working, but the air bags are not - or so I hope.
With this knowledge, and knowing which relays, fuses, and such to test... I feel comfortable purchasing new rear shocks and an air compressor for my 2007 LTZ, regaining the Z55 autoride suspension i have lost.

Although not from my own post, I thank this community much for detailing and providing the knowledge for me to perform the repairs necessary for my vehicle.
 
I do not have an answer to your question.

Maybe a previous owner managed to have the Z55 functions turned off in the computer?

On my 2004 EXT, it came to me with the Service Suspension error lit up when I bought the truck used back in 2012.

I found the OEM air shock bladders completely blown out and the air compressor dead, I am assuming from trying to continuously blow up the blown out air shocks over an extended period of time.

A previous owner was obviously not interested in fixing this and there is no telling how long the air shocks had been blown out by the time I got the truck.

It looks like they had been blown out for quite some time.

IMG_0409.JPG

I opted back then to install a set of air shocks and air compressor from Arnott Industries.

In fact, I replaced all four shocks from there.

The air shocks and compressor served me well up until the beginning of 2020 when the air bladders had both developed small air leaks and the air compressor was also allowing my brand new Arnott replacement air shocks to bleed down overnight.

IMG_4356.JPG

Replacing both air shocks and the compressor has once again set things right.

My first round of Arnott air shocks had lasted had 8 years and over 125K miles, which was longer than the OEM gear did, so I am pleased with the results.

The shocks that I installed back in 2012 came with a set of resistors that plugged into the electrical lines going from the shocks to the computer to prevent a Service Suspension error message from being displayed by the computer.

The current shocks from Arnott plug directly into those connectors in the same manner as the OEM shocks.

My understanding, since these are also not electrically controlled shocks like the OEM shocks, that connector on the new shocks also is a resistor built into the shock to satisfy the computer and prevent it from throwing the error message.

If I manage to get another 100K+ on this same truck and it needs shocks and compressor again, these are the products I will probably use the next time.
 
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