Testing Autoride on an '02 Yukon XL 2500?

[John_McFly]

I have an '02 Yukon XL 2500 6L with Autoride, ~115k miles and the shocks are shot. Under the grime they're orange so I suspect the previous owner (pre-2007 and pre-75k miles) put Monroes on instead of ACDelcos. The entire autoride system is wired up, but I've never gotten an Autoride fault so I'm wondering if the system is disabled or not and want to find out before I drop $1k in shocks.

 

I tried disconnecting the control wire from the top of the right front shock, drove it around, turned it on/off a number of times with no error, then reconnected that and disconnected the right front wheel sensor's wire, again, several start, around the block, turn off runs but no errors on the DIC. Multimeter says one pin of the sensor harness has 5v, the other two 0v, so it's getting power from somewhere.

 

Would a Tech 2 scan tool be able to tell me the system status? I can borrow one from the mechanics at work, but no idea how to use it.

 

On a related note, do I have to disconnect the ball joints and/or remove the tension from the torsion bars to replace the shocks?

[Burbman]

Autoride shocks were OEM orange. Different system on the 2500s, autoride provides Real Time Damping (RTD) not auto leveling like the 1500s.

Autoride has a separate computer, if any problem is detected the DIC message says "service ride control". You do need a Tech 2 scanner since autoride is GM proprietary and not OBDII. I replaced my RTD shocks at 125k miles with KYB. Other good choice is Bilstein, Monroes are too soft for a HD truck. I bought a resistor kit on flea bay where you install a resistor in place of each shock so the system thinks shocks are connected enabling you to avoid any DIC message. Completely removing autoride requires reflashing the BCM to remove the Z55 RPO code so the BCM stops looking for the autoride computer. Yours may have had that done if you are getting no message. I am not sure you can even still buy Delco autoride shocks, the Monroes 40035/40036 are still available on Amazon.

Ps no need to fool with either ball joints or torsion bars to change shocks.

 

Also forgot to mention I have the factory service guide, I can look up the test procedure if you like

[John_McFly]

I actually managed to get an error, just left the sensor disconnected and the error popped up the next day when I was cleaning the frost off. Reconnecting the wire and cycling the ignition cleared it.

Both Amazon and RockAuto have ACDelcos and Monroes in stock, do you think the ACDelcos are worth the extra $200 for the set?

[Burbman]

I have always felt Monroes are too soft, so yes, if you are gonna drop that kind of coin, I would get the Delcos. I have to say I have been happy with the KYBs with AutoRide bypassed, although the ride is a little rougher when empty or not towing.

[John_McFly]

So I replaced the shocks, a few days later took the truck in for an alignment (toe was out on both sides), the next day drove out of town for Thanksgiving and the first time I started it up after we got back, Service Ride Control popped up and now won't go away. I'm betting it's the the front left sensor connection on the frame, since the area had a bunch of dampness of either liquid wrench or brake fluid because when I wiped the area the damp frame coating came away to bare metal and it seems to have infiltrated the wire loom and the backside of the male connector from the body harness that goes into the frame-mounted female connector (that then goes to the sensor). (I replaced the rear calipers in October and spilled some brake fluid down into the engine compartment when bleeding the system) The driver's door and underhood fuses were present and not broken, all connectors in place.

 

I found the 3-wire male connector pigtail (ACDelco PT420) I could use to fix the body harness, is the wire segment from the body harness to the sensor available anywhere, or at least the barbed female connector? And, is there any way to test the sensor itself to determine if it is good?

 

If I hook up the Tech2 scanner, will it tell me exactly where the fault is ("left front sensor"), or just give a generic ("sensors") code?

[John_McFly]

I inspected all of the electrical connections before using the scanner, including disconnecting and looking at both the shock and the connector for the two fronts, Service Ride Control disappeared when I ran a few errands before getting to the shop. No active codes, the codes in the history were C0551 and C0580, for some reason the scanner (Solus Pro) didn't give the following 2-digit specific issue code. 0551 is Option Configuration Error (who knows why that one was set), 0580 is right front solenoid, so it must've had a poor connection to the shock before I reconnected it. I cleared the codes and drove around for a half hour, shutting the engine off and restarting every 3-4 minutes, without the warning returning.

[Burbman]

Mc Fly, glad you got it fixed! I had 2 of the ride height sensors fail over the years and both times the dealer was able to quickly pinpoint the problem with a tech 2 scanner.

 

Sent from my SPH-L720 using Tapatalk

[John_McFly]

The warning came back when I started the truck yesterday (the first ignition cycle after all my test driving), I ordered a replacement front shock pigtail in case that's the issue (there's a TSB that the right front connector can be smacked by an AC line under certain conditions and fail) and I'll get it re-scanned but we might be making our holiday trips without Autoride if the shock turns out to be defective.

[John_McFly]

I seem to have corrected the problem.

 

Looking in the right front shock's electrical connector, one of the metal petals that grip the threads was missing and the other rusty, I bet I broke it when I pulled the connector off before learning that it unlocks.

The shock tested fine at 2.08ohm (acceptable range is 0.7-3.3ohm, I had to wrap one of my probes with tape to make sure I only hit the pin), and after I installed a replacement connector (ACDelco PT1594, note that the original harness will have two colors of wire, the replacement wires are both white, polarity apparently doesn't matter from what I've read elsewhere). The new connector tested fine by varying from 1-9 volts (digital multimeter) on one conductor and the other ground.

 

Connected everything up, message still popped up, took it apart, double checked everything with the multimeter vs the left side's numbers, put it back together being extra careful to line up the ground wrench flats on the shock with the upper wings of the connector before locking it (wings perpendicular to the flats), then I turned the connector (<1/8 turn) until I felt just a hair of resistance to make sure it was aligned properly and getting a good grip. 10 1-minute-on-1-minute-off ignition cycles without the error coming back, a few trips around the block and I think it's fixed.

 

One note, from what I have observed, running the vehicle for less than 30 seconds seems to reset the fault counter to zero and cause the message to falsely disappear for 3-5 ignition cycles.

[5Alive]

John_McFLy... outstanding can do perseverance diagnosis, and repair. Likely more methodical and procedurally correct than what one might hazard at a GM dealer. Thank you for posting the nitty gritty details. Subscribed for future reference.