Yep, sounds just like ABS kicking in.

 

Tonight on my way home I tried the HDC again, this time I waited until I was already descending the hill before I engaged the HDC, still not change in circumstances. The green HDC light just flashes repeatedly followed by a constant chiming. During this experiment however a pending code poped up on the UltraGuage: P0501. I looked it up in the search and only came back with a hand full of threads, only 1 relevant by bballjames. DiscoMike told him it was likely a "speed sensor range/performance, VSS" and that he would lose his forward gears soon. Next day the pendding code disappeared and there was no resolve to the code so do you guys have any input here? Could P0501 be linked to a fault in the transmission or a fault with the HDC? Seems this is becoming a deeper plot and I need to get to the bottom of this - preferably without being stranded like last time when the CPS failed.

One thing else I noticed is that its a royal pain in the *** to shift the hi/low range shifter. Would not move at all when I first purchased the truck so I saturated the linkage with liquid wrench and worked it for a couple days then it freed up nicely. Ill try repeating that procedure again to see if it helps.

Thanks for the support and any advice you can give.

 

The way I see it.
If you have to put your truck in Low range for HDC to work, you might as well just shift to 1st or 2nd gear and let the engine to the braking. No need to put the excess wear on the brakes, etc.

Engine braking is superior to using the brakes on a steep incline, IMO. Down hill braking comes with its own risks... Such as a sudden shift of weight from back to front which could EASILY cause a roll-over scenario (seen this happen twice). Even on the steepest decent down mountain cliffs in Colorado and Moab, I always/only use 1st gear in Low Range.

HDC and general braking down hills will smoke your brake pads in no time.

They put warning signs on the highway all the time "Trucks use low gears" for a reason.

 

Julian, do you have the 3 amigos on? Like ABS light or TC light on?

 

I second this... Although, if it were my truck, I'd want to know the reason the system is not working, just to be sure it's not a deeper problem that will cause mechanical or safety issues in the future.

But, as mentioned, when I've tried HDC, it does seem to use the brakes a LOT. I'd rather let the gears and motor do the holding back.

With that said, it does seem pretty safe if it's just a steep incline without any major bumps. When there are large bumps, the HDC allows the vehicle to go too fast, 5mph+, and it throws you around the cab pretty bad.

Without bumps, it does a GREAT job of keeping your speed on track and applying the correct braking to keep the vehicle going straight down the hill. I've tried it on icy/snowy hills, and it works fantastic. I would have to try it again, but it seemed to me that it applied the brakes ONLY to the wheel needing it. In other words, when it started to shift sideways, the correct brake was applied to help it straighten up again. Could just be my imagination, but that's what I was thinking it was doing on the ice. Like Traction Control in a sharp turn.

 

At the moment no amigos. They did come on awhile ago when my front caliper burst, but I have since replaced front calipers and brakes and had DAP flush the brake fluid and reset the 3 amigos. That was over 7 months ago and the amigos have not come back since. TC appears to be working as it should, I remember it working this past winter. Im gonna try setting that pending code and see if it comes back.

 

New development in the brakes saga. Apparently the rear pads are thin and the rotors are showing uneven wear. Now we're back to the grinding sound though its not to bad YET. I just replaced all the pads and rotors front and rear less than a year ago, and factor in that the truck sat for 5-6 months while I was away. So either the brake rebuild kit I ordered from AB was cheap as **** or driving the truck with a bad brake booster servo, (new brakes installed though) put extra strain on the brakes. Funny thing though the front pads are still thick and the rotors are shinny and show even wear. Could also be failing calipers but its unlikely that both rear calipers would fail at exact time. So far the rear calipers are the only brake parts I have not replaced, replaced the front pair awhile back. Im running cheap at the moment so Ill have to suffice with another cheap rebuild brake kit though just for the rear. $155 gets me rear pads and rotors shipped so ill do that next week.

Just got the truck inspected the other day, and today the pending code P0501 returned! Not much input on the forum about this code so it would seem that its a less common fault code. Could someone please shed some light on the matter for me?

 

OBD-II Trouble Code Technical Description
Vehicle Speed Sensor Range/Performance

What does that mean?
Basically this means that the vehicle's speed as read by the Vehicle Speed Sensor (VSS) is not working properly.

 

Ive heard that on the D2 the speed sensors are on the abs hubs whereas on the D1 its located on the transmission. So could this mean one of my abs lines is bad? Or are we talking about an entire hub replacement? Is there any way to pinpoint where the fault is?

 

If your ABS lines are bad then you'd have the 3 amigos, which you mentioned you do not.