alvocado

I bought an Actron CP9680 which can read manufacturer drivetrain codes. I found out the 4wd selector switch on the dash was bad which is a common part failure that causes the Service Stabilitrak error message. The wiring on the back of the switch degrades and the faulty connections send incorrect voltage back to the transfer case control module resulting in the dash error. The dash selector is around $25 and takes 5 minutes to replace. The Actron can be bought on Amazon and is well worth the investment.

This sounds like a motor mount and similar to what I experienced earlier this year. I thought it was the slip yoke but the driver's side engine mount was shot. I had hydraulic fluid from the mount leaking down onto the front diff for over a year and couldn't figure out the source. Some fluid would end up on the ground and looked like a dried orange/brown color. Check for signs of dried fluid on the top of the front diff.

I have a clunk under the driver's side ('11 Yukon 4WD) during very low speed turns, e.g. pulling into or out of a driveway, and suspect it's coming from the steering rack. The lower control arm was just replaced and the shocks were replaced with new mounts within the past 2 years. There are no other steering issues to indicate the rack is bad. Does anyone have experience installing the Dorman steering rack bushing kit, part 523-267? It's not clear if the rack has to be removed to replace the bushings and if removal of the old bushings is worth the effort. I see the kit comes with the metal bracket but can't find any install instructions. 523-267-007.jfif

1 and 7 would show oil fouling if the AFM solenoid was passing oil so I figured I'd start with one of those and check a nearby for comparison. The wires are original.

I'm trying to diagnose a rough idle and would like some input from those who've chased down similar issues. I ran an STP Pro Series intake cleaner and two bottles of B12 in the fuel tank to clean up valves and fuel injectors. The idle is still a little rough with some consistent missing. Drive RPM seems fine with no noticeable issues and no codes. I pulled cylinders 1 and 3 plugs which have 55k on them, OEM AC Delco and the electrodes appear fine. There's a little carbon on the bases so any input on whether or not this is an indicator of minor carbon fouling and potentially a leaky injector would be appreciated. The truck has 155k miles, no issues in 10 years and no oil consumption.

Sage advice. I had the same error for over a year and invested in an Actron scanner that can read GM manufacturer codes. I found the electronic switch that changes from 2wd/auto/4wd was bad and replaced it for less than $30 and a 5 minute repair. The switches are a common failure point. They communicate with the controller by sending voltage signals that correspond to the setting. When the voltage doesn't match the switch setting, you get a Service 4wd message on the dash. The Actron CP9680 will read manufacturer codes and it's $115 on Amazon. Much cheaper than all the parts you've replaced.

It's definitely the alternator. I had the pleasure of changing the P/S pump 3 times in the past two months after getting two bad replacements and the pump is finally dead quiet. The whistle sounds like I have a turbo charger on the truck and it's easy to isolate when listening up next to the alternator. I put a stethoscope on it an the bearings sound normal. No noise when spinning the pulley with the belt off either.

I have a 1 year old OEM 160amp alternator that is whistling on my '11 Yukon. The whistle varies with RPM and is audible from cold start as well as warm operation. I ran 3 consecutive voltage tests with my Actron and pulled the following data: K0E0: 11.8, 12.9, 12.6 Cranking: 8.5, 8.8, 8.8 K0ER: 14.7, 14.8, 14.8 I did not detect any AC voltage at the battery terminals using a multimeter which would indicate a bad rectifier. Any thoughts on how to troubleshoot the whistle including confirming if the alternator is bad would be appreciated.

To close the loop, the pump was defective. Pump #3 is dead quiet. It's unfortunate that 2 of 3 new AC Delco pumps were duds but I guess that's what we get with inexpensive made in China parts. For anyone considering buying from Rockauto, it's not the best experience if you encounter more than one warranty issue. You have to pay for shipping for both replacement parts and to return the defective parts. Worse, there is no option to request a second warranty replacement for a part that is still within the warranty period and Rockauto offers no email or phone customer support. I spent an additional $25 shipping parts and waiting for days which was no cheaper than buying locally. A better option for auto parts is Amazon which is free Prime shipping, they cover shipping both ways on warranty parts and they don't charge you for a replacement as long as you return the defective part within a week.

2011 GMC Yukon: I've replaced my PS pump twice in the past month with new AC Delco, OEM units and the second pump is still noisy. I've flushed the system completely, used Valvoline PS fluid, replaced the pressure and return lines, used new seals on the lines at the reservoir and steering rack, and bled the system at least 5 times. The pump still whines especially when turning. There is no sign of air in the reservoir (bubbles or foaming) nor any sign of fluid leaking. Are these made in China pumps that unreliable or am I missing something? There could be air pulling into the system at one of the hose connections without a visible fluid leak but I would think that would result in air bubbles in the fluid. Any thoughts are appreciated. I dread the idea of pulling this a third time and dealing with the inconvenient Rockauto return process.

Since the GM part is $7 for one o-ring, I found a suitable substitute from a Harbor Freight HNBR o-ring assortment set for those who need to replace this seal. Here are the specs: GM part: 7.65mm ID x 1.63mm thickness (0.301 in x 0.0642 in) Standard HNBR #A011: 5/16" ID x 1/6" thick (0.3125 in x .0625 in) You can buy the 205 piece set for the cost of the single GM part.

I removed the pads, cleaned the caliper bracket and shims, lubed the shim surface and pad ears and reinstalled. No change.

The slide pins looked identical to me and made no noise when manually moving the caliper with the piston compressed to allow some movement while mounted. I've removed, cleaned and lubricated the pins twice with no change. The sound appears to be coming from the caliper body when I listen with my ear next to the system. In my experience, failure to clean and lubricate the pad mounting surface on the caliper bracket would only cause squeal due to pad vibration. The brakes were bled last summer but I may bleed this corner to make sure fluid is flowing through the caliper properly. There are no unusual marks on the rotor or pulling due to uneven braking.

My driver's side rear brake on my '11 Yukon is making a creaky noise when activated and I'm out of ideas on the cause. I cleaned and lubricated both guide pins but it didn't help. Both pins slide as expected and don't make noise when moved manually. I pulled the caliper again today and inspected and cleaned the piston. The piston seals look fine with no leaking, bulges, etc. The piston surface cleaned up with brake cleaner and depressed easily prior to removal with a c-clamp. There aren't many moving parts so I'm out of ideas other than the entire caliper may be bad. Here's a video with the tire off, truck on stands and my son depressing the pedal fully to the floor. It sounds like an old bed spring. Any ideas are appreciated.

I replaced the P/S pump and hoses on my '11 Yukon and the Gates pressure hose did not come with a new oring for connecting at the back of the pump. I reluctantly reused the OEM oring but it is not sealing. Does anyone know the spec for this oring, size and material or if it's possible to source just the o-ring? Searching has not turned up any information. I have an NBR o-ring assortment if the material is compatible with P/S fluid.

To clarify, the "creaking" noise from the original post is not from the pads or rotors as it happens while parked and depressing the brake pedal. Brake squeal when applying the brakes to stop or slow down is a result of the pads vibrating which does not necessarily indicate the brakes aren't working correctly. If your brakes are in good working order and you get squealing when applying, it's either due to the material (harder pad composites), product design (no or inadequate backing material on the pads), or shims (caliper surface not properly cleaned and lubricated when installed).

The brakes on fullsize GM trucks last a long time which is great with one downside: you don't regularly service the components since you aren't changing out pads very often. Here's a picture of my rear caliper guide pins showing the factory lube is mostly gone and what remains is hard and worthless. I pulled these today to clean and lube with correct caliper guide pin grease (used Permatex green brake lube). When swapping my front setup to a PowerStop z36 kit yesterday, one of the front guide pins was rusted near the head and had no grease remaining. That was likely an issue with the guide pin boot letting in moisture combined with no lube so all were replaced with the new boots from the PowerStop kit. It takes about 30 mins to maintain the guide pins per axle and inspect the boots and I recommend doing it at least every couple of years if you aren't changing brakes. This resolved my rear squeak issue.

Did anyone ever resolve this? I have a creaking noise from the drivers rear brakes when applying the pedal. It happens while parked and is consistent with pedal application. I doubt it's pad related since the creak occurs when the vehicle isn't moving. The GM repair guide does not note anything about caliper guide pins requiring lube and pistons are lubricated with the brake fluid. I'm interested to hear if others with the creak found a fix.

It sounds like your only option is to adjust using the star wheel on the parking brake shoe. Pull the rotor, and adjust the star wheel so the shoe diameter increases. I adjust it out until the shoe just drags on the rotor then back it off slightly. You can set the rotor in place and spin to check clearance.