New Silverado Owner, got some issues that need sorting out

Discussion in 'Technical Discussion' started by Ziggy, Apr 12, 2016.

  1. Ziggy

    Ziggy Well-Known Member

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    If you check out my thread in the Pictures section, you'll see I just bought a Silverado RCLB that my son will be driving primarily. Before I'm willing to turn it over to him though, there are a few issues that I'd like to get sorted out first.

    1) Three times today, all at low speeds, the truck has activated the ABS at inappropriate times, nearly causing me to hit something. Now, when I test drove the truck yesterday, I noticed a growling/rumbling noise that increased in volume and intensity as I accelerated, but I attributed it to the knobby, off road oriented tires on the truck. At this point, I believe it needs at least a left front wheel hub and bearing assembly, and maybe the right as well. That said, I know the ABS wheel speed sensor is integrated into the hub and bearing assembly. Could it be that the bearing is bad enough to send a faulty reading to the ABS module and activate the ABS when coming to a stop from slow speeds?

    2) Service 4WD light on the Message Center - The truck goes into 4Hi, and will go into Auto 4Hi, but once there, doesn't want to switch back to 2Hi. I feel like I read somewhere this could be a bad switch on the dash, and replacing it will remedy the Message Center warning, but I'm skeptical. Mostly because I had to replace a front axle disconnect, TCCM, and both front hubs on my Trailblazer to remedy a similar issue.

    3) Windshield Wipers only work on Hi. No intermittent wipe, no washer spray, just ON. As I understand, this issue is likely the Windshield Wiper Module, or some such... I spotted a $20 Dorman part on Rock Auto, but looking under the hood today, I didn't see anything that looked like the part photo online. Where is this thing located? If you've got a couple photos for reference, it'd be appreciated.

    If I can get these things sorted out to my satisfaction, I'll let the boy take over driving the truck, but until then... I'm not willing to take the chance.

    Here you go, GMTN, the driving fate of a 16 year old boy in Ohio is your hands, help me out!
     
  2. littleblazer

    littleblazer Gold Supporter

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    Auto transfer case is like ours. Granted I don't konw the details of how it works. The hub could cause the issue or if they are larger than stock tires maybe it's messing with the abs? The wipers I'm not sure on.
     
  3. Sparky

    Sparky Moderator

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    ABS could easily be caused by the screwy hub. I'd have that happen on my Trailblazer at low speed stops sometimes even before the hub started actually making noise. I'd start there.

    The other source could be the actual ABS module itself. The GMT800 trucks (and others around the same period with the same module) could develop cracks in the solder in that module which could cause all sorts of wacky things like that. My coworker's 2004 Silverado has that problem. The "official" fix is to replace the module at a lovely price. Or, the easy cheap fix is to resolder it and be done. You don't have to pull the entire ABS block or mess with the brake lines I dont' think, just remove the brains component from it. Typically if this is the problem though a scan with a tool able to read ABS codes will show an ABS module code stored (bluetooth adapter and Car Gauge Pro on Android will do it).

    The full size does not have a disconnect like the GMT360 platform does. All that disconnect stuff is part of the front differential unit, which also makes it much more durable and less likely to internally burn up because it is all properly lubricated with gear oil. There is still an actuator on the passenger side of that differential to engage/disengage the axle. When I bought my GMT900 the sales guy said there was an issue with the 4x4 caused by a faulty dash switch which they had on order and would have fixed before I picked up the truck, so it very well could just be the switch in your case too.

    I'm assuming you checked fuses and such for the wiper washers etc... so this one I'm not sure on or how the system works. Blaming that module makes sense though.
     
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  4. Ziggy

    Ziggy Well-Known Member

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    Regarding the noise and ABS funkiness, I'm going to start with hub and bearing assemblies for the right and left. Watched a Youtube video, and was pleasantly surprised at how simple the replacement operation is compared to the GMT360. Have had pretty good luck with cheapo bearings in the TB, so will probably go with the Approved Performance bearings on Amazon (2 for $106!) just to get this thing on the road. As to the wipers, if the Dorman module is only $20, I figure I try that, and if it doesn't take care of it, then no big deal, and if it does, BONUS!
     
  5. littleblazer

    littleblazer Gold Supporter

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    The hub is similar to the 360, more room though. but the hub itself rests firmly in what its mounted to vs. loosely. I used a 10lb sledge on the escalade to get it to budge. It can be a bitch depending on age.
     
  6. Ziggy

    Ziggy Well-Known Member

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    I've now replaced both front hub and bearing assemblies. Fortunately, I have access to a lift, and was able to get the truck up to where the front end is chest height. Passenger side appeared to have been done before, operation was still quite smooth, and the assembly popped out after a few whacks with a 3 lb. hammer. The driver's side was another story! I swear it must have been original to the truck. I tore off the rusty dust shield so my son and I could alternate hitting the back of the hub with a pair of 3 lb. hammers, and all we ended up doing was knocking the hub out of the bearing housing. It took about a half can of PB Blaster and an air hammer with a chisel attachment to get the bearing housing out of the knuckle. Spent about an hour doing the right side, almost 4 doing the left side, not including the time spent going to buy an air hammer. After all of that, I took it for an alignment, and found that the right front inner tie rod end, and upper ball joint were worn and loose. So this past weekend, I replaced inner and outer tie rod ends, and upper control arms on both sides. Getting the upper ball joint separated from the knuckle on the left side was a very similar experience to the hub and bearing assembly, unfortunately. Taking it for a professional alignment this evening. Fingers crossed, there won't be anything else hiding!
     
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  7. Ziggy

    Ziggy Well-Known Member

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    Mixed bag on the alignment results. Camber and Toe came in just fine, but the Caster measurement on both sides is out of whack. Caster isn't a tire wear measurement though, and the truck goes straight down the road, so I think I'll not sweat it too much for now. Bought the Dorman wiper motor pulse board and swapped it in. That was definitely the problem, because the wipers are working now. We'll cross our fingers and hope to not be doing the pulse board again in 6 months. Still have a couple of lingering issues, but I think I've got at least a trail to sniff out on both of them.
    1) Service 4wd displayed on the message center. From what I've read, I believe this issue to be a faulty dash switch. I've been able to get the truck into 4wd and into A4WD, and with some patience, back to 2wd, so it seems the switch is the logical place to start. will try to come up with one from the junk yard next time I go.
    2) Service Engine Soon light - scanner pulled a code for the Evaporative Emissions Purge Valve. Don't remember the exact code, but when I was under the hood the other day working on the pulse board, I found a vacuum line with a split running lengthwise on the top, on the left side of the intake cover. If I'm not mistaken the vacuum connector attached to the purge valve directly, so I'll replace the fitting and try to clear the code.
    Other than that, I just submitted the boy's high school transcript to my insurance company... With 3 weeks of school left this year, he's carrying a 3.36 GPA, and he's managed to get himself a job, so I suppose I've got to let him drive it now. Wish us luck!
     
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  8. Sparky

    Sparky Moderator

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    It sounds to me you're on the right track.
     

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