Rear spring broken? (Also ABS question)

[Mike534x]

So for the last 2 weeks, I've been getting a popping/clanking sound coming from the rear. Doesn't matter if the road is smooth, bumpy or has a few cracks and whatnot. Thought it was my rear sway bar links. Both sides are solid, so my next look around had me checking up the upper and lower control arm bushings. Everything looks solid. Noticed something odd about the rear springs. So first image is the driver side, and the other two are of the passenger. Judging from how the right spring is sitting, does it look like it's shifted, or broke a coil???

The truck originally had air ride, then in 2015 or 2016 the original owner converted it to springs using the Monroe kit.

I'm also dealing with another issue and that's the ABS light coming on and staying on for 3 minutes after startup, and sometimes while driving down the road. Is Torque able to read the speed sensors, or is there a recommended scanner for a decent price capable of reading ABS codes? My only assumption so far, is that one of the front hubs has a bad speed sensor.

 

[TollKeeper]

Spring Perch cup/insulator/isolator is missing. Easy to fix. Spring is fine.

Cant help you on the ABS.

I think this is it... One of the other guys will have to verify..

Genuine GM Rear Coil Spring Lower Insulator 13377312 | eBay

Without awd. Without slt. This GM Genuine Part is designed, engineered, and tested to rigorous standards and is backed by General Motors. Your use and browsing of this parts catalog is at your own risk.

www.ebay.com

 

[Mike534x]

I wasn't aware there was a lower spring insulator for these trucks, I know there's an upper one. I don't see one on the TB either. Hard to tell with the right side because I can't tell if it's the orientation of the spring, or what but it looks off compared to the driver.

 

[TollKeeper]

I guess I could be wrong. But if it was converted, the perch has a different design, and I would think it needs the insulator to fill in the gap.

 

[mrrsm]

This Video might offer some additional views of that area with more information on the Rear Coil Spring R&R Hardware and Coil Spring Orientation:

 

[Mooseman]

My 9-7x had already been converted and I don't remember a lower isolator, nor do I remember one on any of the other GMT360/370's I have owned. One of those springs broke and I replaced them with my old EXT springs which jacked the rear stupid high. The engine died before I could replace them again. Maybe the Monroe springs break easily?

 

[Mooseman]

Spring Perch cup/insulator/isolator is missing. Easy to fix. Spring is fine.

Cant help you on the ABS.

I think this is it... One of the other guys will have to verify..

Genuine GM Rear Coil Spring Lower Insulator 13377312 | eBay

Without awd. Without slt. This GM Genuine Part is designed, engineered, and tested to rigorous standards and is backed by General Motors. Your use and browsing of this parts catalog is at your own risk.

www.ebay.com

Checked the fit info and it says it doesn't fit GMT360 so I don't think they had one.

 

[Mooseman]

For ABS sensor issues, you could get an ELM327 bluetooth adapter and the Car Gauge Pro or Chevrosys app on Android or @TJBaker57 could walk you through how to scan for those codes using another free method.

 

[Mike534x]

I'm gonna try getting back under to inspect her tomorrow, to me I just can't recall the passenger side spring sitting/looking the way it is. I've never had experience with Monroe springs, but after seeing the struts take a dump after 3 years I would be shocked if the springs are gone. I'd be easier to tell if it weren't for the springs flaking, because it looks like it's cracked on the lower left side but it's just too hard to tell without getting closer from a better angle.

Thanks @Mooseman , I believe I had the page TJ linked awhile back to input the values into Torque saved somewhere. Feels hard to have a "quiet" winter without something breaking/failing.

 

[TJBaker57]

Is Torque able to read the speed sensors

Well, not natively, it cannot.

While there are some PIDs in Torque that claim to represent individual wheel speeds, at least for our platform, the values returned are not correct. In fact, for our platform all 4 of the "GM wheel speed" PIDs in Torque are actually reporting the speed of the vehicle, not individual wheel speeds.

That said, for my 2002 with the system having only a single rear speed sensor, I have determined a means of reading the 3 sensors using Torque but with a very specialized 'PID' setup.

The setup would probably also work with the later models that have 4 wheel speed sensors but I have no means of testing that.

I cannot remember if I ever posted up the setup I just spoke of. I'll have to look when I have a little time, too late tonight.


Now then, if you already have Torque Pro it follows you have an OBD2 adapter. There are a few apps that will do the deed for you and read the EBCM (ABS) codes as well as most (maybe all) other systems codes.

Additionally the current version of Torque Pro now includes a serial terminal within the TorqueScan plugin. There, given the proper instructions, you can read the codes out yourself.

If interested just let us know!

 

[Mike534x]

Much appreciated fellas! I haven't had a chance to look at the Envoy yet, we actually managed to get about 4 to 5 inches of snow today, so I've got her parked in the garage until I get a chance to look at her in the morning while I haul out the torpedo heater. I've downloaded the Chevrosys app to play around with, and I'll peak at those PIDs for Torque tonight.

If I can just get it to read the front wheel sensor values, it'll help me at least figure out which of those hubs is acting up or at the very least figure out if this is an ABS module problem.

 

[TJBaker57]

If I can just get it to read the front wheel sensor values

Well that's the rub right there. The EBCM does not report live data in the way that other modules do.

That is why I have to have a very specialized setup for Torque Pro (or any other app) to read live data for an EBCM.

If there is a problem with a wheel speed sensor there should be a code stored for it. Chevrosys Pro should read that.

 

[mrrsm]

If you can get the Envoy inside of a Dry Garage... These Basic Step By Steps should work on ANY Wheel Speed Sensor that uses a Fine Wire A/C Coil generating Very Mild A/C Voltage from any spinning Reluctor Wheel in Close Proximity to the Plastic Encased Tubular A/C Coil Pickup mounted upon the Wheel Hub:

(1) Safely Elevate your Envoy on Jack Stands, Turn the Wheels to the Right.
(3) Unplug the Front Wheel ABS Harness Assembly Two Pin Connectors.
(4) Set your DMM to OHMS & Place Leads on the 2 Hub ABS Harness Connector Pins.
(5) THIS Reading should be around 1,000 OHMS.
(6) Switch the DMM to A/C Voltage & Keep the Leads on the 2 Hub ABS Connector Pins.
(7) Hand Spin The Driver's Side Tire to around One Rotation Per Second.
(8) The Teeth on the Hub Internal Reluctor Wheel should create A/C at 450 Milli-volts.
(9) If the A/C Voltage is LESS than 450 Milli-volts, Remove the Brake Calipers & Disks.
(10) Support the Brake Assemblies with "J" Hooks & Carefully Unbolt the ABS Sensor.
(11) Remove the RUST under the ABS Sensor Mount on the Wheel Hub with Abrasion.
(12) Plug the Hole into the HUB while using a Wire Wheel or Sand Paper to remove RUST.
(12A) When the Hub is Clean and Shiny, Wipe the ABS Sensor with a Cloth & Brake Kleen.
(14) Apply some Brake Pad Lube around the ABS Sensor Base and Re-Mount it to the Hub.
(15) Re-Install the Wheel-Tire & Hand Spin Wheel @ around One RPS with DMM attached.
(16) If the A/C Voltage reads At or Above 450 Milli-volts... THEN SUCCESS!
(17) Re-Attach the ABS Harness to Body Harness Plugs and Re-Install the Brake Hardware.
(18) Install the Wheels-Tires & Follow the Lug Torque Specs per attached Lug Torque PDF.

This Dude takes us through ALL of these Steps in THIS Video:

NOTE:

If you determine that the Problem concerns a Damaged or Inoperable EBCM... Follow THESE R&R Instructions to avoid making matters worse by using incorrect removal procedures:

 

[AmpOverload]

If I can just get it to read the front wheel sensor values, it'll help me at least figure out which of those hubs is acting up or at the very least figure out if this is an ABS module problem.

For what it's worth, I'm going to join the folks suggesting that you check those ABS/EBCM Diagnostic Trouble Codes (DTCs). I know that sounds obvious, but I'd go so far as to say that you should do that even before you try to read individual WSS (Wheel Speed Sensor) values.

I say this, both to you and any future readers of this thread, because WSS issues can often be very subtle, so much so that it won't be obvious just by manually monitoring the 4 WSS values, unless you're also graphing them (and I don't think that even ChevroSys Scan Pro can do that). But the ABS/EBCM is typically very observant of even subtle WSS discrepancies and will set 1 or more DTCs (and light the dashboard "ABS" lamp).

My most recent ABS issue was a mis-behaving right-front (RF) WSS. The ABS node was correctly reporting 2 DTCs, both related to the RF WSS. A 5-minute recording of WSS values, when graphed, shows how subtle the issue was:



The top line (red) is Vehicle Speed Sensor (VSS) from the PCM. The other 4 lines are WSS values from the ABS. The "RF-WSS" value (3rd line from the top, in blue) has small perturbations at 2 points along that timeline, both of which would have been incredibly easy to miss if I were just manually watching 4 WSS values.

The issue was fixed simply, by gently bending the WSS connector's "pins" and spraying some CRC "QD Electronic Cleaner" in the connector. No sense replacing an entire wheel hub with integrated sensor when the issue was so easy to fix, right?

Obviously, your problem may not be that subtle (or that simple to fix), but I wanted to mention my experiences, in case it helps someone/anyone. Good luck with your diagnosis!

 

[Mike534x]

Update time!

Well, the good news is the rear springs are fine. Found the culprit(s), the passenger rear sway bar link is shot. The lower half of it is still nice and tight, but the joint has play in it near the top where it mounts to the frame. The sway bar bushings are also shot, so I've got a bit of play in the bar itself when grabbing it and trying to move it.

I ended up driving her over to the shop, and having them scan/check the ABS codes while I was getting an oil change done. The code is for the passenger front speed sensor. Both front hubs are brand new too (left side is a Timken, right is a Moog). Roughly 500 miles have been placed on them since the install back in October/November.

If the sensor itself is bad, it may be more feasible to replace the sensor then getting a new hub assembly? I'm not sure how well the Moog hubs play nicely with new sensors. The last time I tried replacing a speed sensor on a Moog hub, it ended up not fixing anything.

I was also informed, that my power steering lines are starting to develop a minor leak (already knew they were going bad), but it looks like the rack and pinion is starting to develop a small leak. I'll be making a new thread on that soon, I take it the job should be much easier to do on the V8 vs the I6? They quoted $2k to replace the rack and lines.