Just bought first GM truck, looking for some advice

troverman · April 25, 2018

22 hours ago, davester said:

Regular power steering fluid is fine.

You may want to flush the power steering system, as it is also used to boost your brake system (instead of a vacuum booster). People think (including me, having done this) that flushing the system gives a little firmer brake pedal.

You might also need to bleed the ABS controller. The proper way to do this requires something like a tech ii or Autogenuity with GM enhancement or something similar (they can command the computer to pulse the abs system a special way), then you bleed all 4 corners again.

Thanks davester, I can see this one is a hydroboost unit. I suspect there may be air in the ABS modulator since I removed the modulator and disconnected all lines to it. I wish there was a way to turn on the ABS pump and cycle all the solenoids...but there isn't. I'm going to drive the truck a little, then rebleed...hoping the air moves into the lines.

I'll add some standard power steering fluid and see if at least the noise goes away.

19 hours ago, racetrk said:

You can get a Delphi reman cluster on rock auto for under $200.

Thanks for the tip, a little late now. I use rockauto but did not see the cluster until I searched for it. With the core, the prices are about the same but the company I use is not giving me much back on the core. Then again, the plexiglass is broken so maybe it has no value. At least it was shipped fast.

troverman · April 25, 2018

I did also work on the truck briefly last night. Installed the new cluster and discovered the oil gauge is all over the place. Reads 80, then 0, then 40, then 0, then 80. Oil pressure low message is displayed along with the beeps. So I believe I'll need a new sending unit. The cluster otherwise looks nice and everything works perfectly.

Spent most of the time welding in a new slip-on, heavy-gauge rocker panel. Quite a bit of prep work just getting the thing to fit was needed. I also measured where the final exhaust tailpipe muffler hanger needs to be welded on and did that as well.

Pretty much all that's left is just sorting the lights that aren't working. I'm guessing its ground wire issues.

davester · April 26, 2018

The "redneck" method of bleeding the abs controller is to go to a gravel road and then hit the brakes several times hard enough to activate the ABS system.

So, the overall bleeding process is:

-bleed all 4 corners, starting with the passenger rear caliper, then driver rear, then passenger front, then driver front

-bleed the abs controller, either using a computer or the redneck method

-bleed all 4 corners again, in the same order

troverman · May 4, 2018

So I finished the body work and got all the lights working. Cab lights weren't working because an under-hood fuse was missing. Dump clearance lamps weren't all working because of a corroded harness. Turn signals required a new converter unit in the harness. Found out my passenger side fender is all rotted out under the plastic flare...

Was able to get the truck through inspection without issue. The brakes feel pretty good, actually. Besides still having no blower and no wipers, the two new issues I noticed are a slight looseness in the steering over bumps. I'm thinking the pitman arm ball joint is bad? Remember, the truck has all new upper/lower ball joints and tie rod ends. The other issue is that the engine seems to really "roar" like the engine fan clutch is permanently on. With the engine off, you can manually move the fan, but it doesn't move easily.

troverman · May 7, 2018

So I drove the truck and it started misfiring after a few miles going up a hill...blinking Check Engine light. Codes said misfire on #7. I'm assuming it needs a coil pack, so I'll buy one this afternoon. Otherwise, seems to run good. Still working on wipers and blower. If you turn on blower, you can hear the fan turn on very slowly but then on higher speeds it just stops. Either the blower or resistor is bad. Wipers I'm not sure about...washer doesn't work either.

troverman · May 21, 2018

Here's an update. The misfire turned out to be a bad fuel injector (debris on the intake side of the injector) but I didn't figure that out until I replaced a coil pack and all the plugs and the MAF. Truck is running well now.

I've done a little more work to the appearance of the truck and it is improving. I replaced the blower resistor and I have a blower. The blend motors don't work right, though. Job for another day.

ExtraSlow · May 23, 2018

Cool, keep us updated.

troverman · May 23, 2018

So I got the wipers working last night. Despite having already checked the fuse and even replaced it with a new one, that's where the problem was. The female fuse holder was not holding the fuse pins securely and not making contact on one side...so power was not transferring across. Using a pointy test light probe, I was able to bend the fuse box pins inward so better contact was made. Wipers work fine now.

Dropping the truck off to a fabricator next week to replace the dump body floor and do some patching along the walls...then I'll coat the entire exterior of the box with black bed-liner material.

Here's a shot of the truck towing one of my tractors the other day...a bit heavy for the old 6.0L and 4L80, but besides being a bit slow it did fine.

ExtraSlow · May 28, 2018

That's an annoying thing to troubleshoot, the fuse-holder. Glad you found it, and glad it's already doing some work.

troverman · July 12, 2018

Another update: the truck doesn't get used a lot, but it has been completely reliable and solid. Ended up having a body shop buy me a capa-certified fender and paint it victory red to match the rest of the truck. Installed it to replace the other fender which had totally rotted out under the flare. So that fender looks a bit brighter than the rest of the truck. Wipers are still working fine as is the blower. I can get the blend motors to go between face vents and the floor, but never to defrost. I'll need that working by winter. Dash removal is probably going to have to happen.

I ended up replacing the four radio speakers as a couple were blown, so that sounds better now. Going to have to replace the headliner...it is so grimy. Just going to buy some new headliner cloth and re-do it myself.

Still have the odd throttle cut-off when the pedal is floored or mostly floored. Still don't know if the rear fuel tank works or not. But pretty happy with the truck.

bg1988 · July 30, 2018

On 4/24/2018 at 5:46 AM, troverman said:

Adding another update, if anyone cares. Finished installing the rear axle "home-made" brake lines, added fluid, and bled the brakes. The pedal feels spongy, but stops the truck. Since I've never owned a GM truck before, and this one had a split brake line when I bought it...I really don't know what it should feel like.

The muffler I bought really isn't designed for this truck. The dual inlets are the right size, but spaced much closer together than the muffler coming off. I've pulled the pipes together enough to make it work, and the muffler is clamped on and not leaking, but it is less than ideal.

The power steering pump is howling a bit. I'm hoping its just low on fluid. It looks like a lot of gunky oil on one of the lines coming off the pump. What are you supposed to put in the pump? The manual says "GM power steering fluid" whatever that is.

Now I've got to figure out how to fix some electrical issues. I have rear tail lights and backup lights, but no rear turn signals or rear four ways. I also have no cab clearance lights; otherwise all exterior lights work.

its normal to feel that way when i first had my 04 it was this way 1500 series it's the same on the 06 shitty e throttle bs, on my impala the brakes bite the rotors very strongly with minimal throttle lag time. compared to the pickup I had to readjust my self because I was "braking hard on that car" the throttle response sucks too on these trucks.. I have to push the gas before releasing the brake peddle or you risk rolling back into the car behind you. or even stalling the engine..

I drove my uncles 2001 v6 and it did not have this issue

it's drive by wires.. slow as hell though. only topped out at 65mph like 0 to 60 in like a mile with no load

Edited July 30, 2018 by bg1988

troverman · September 12, 2018

Figure it was time for another update. I had another used dump body installed that is more solid. In the process of grinding and painting. New LED rear lights installed. Found a good deal on a complete set of OEM GMC wheel center caps and installed those.

The truck always started a little slow; assumed it was the Wal-Mart 600CCA battery going bad. It got to the point where it was very slow, so I installed a new red top Optima 800CCA battery. I hate the side terminals. It did not improve the starting whatsoever! I ended up installing a new starter; it fire up like a dream now.

I got the defrost function to work now. I just kept making the blend motors try...finally it is freed up and I can set the air position to whatever I want. Did not need to disassemble dash...happy about that.

The axle seals are leaking on the driver's side. Should have replaced them when I did the brakes...oh well; I'll pull the axle and replace.

I did remove the throttle body and spray the heck out of it with throttle body cleaner. Some people have cautioned not to manually move the butterfly or you need a GM tool to reset. Well, I did it, and the truck wouldn't start. Feathering the throttle caused it to start and it is running fine. Maybe a tad more responsive at low end, but it is still cutting out at the high end like it hits a governor. Maybe the throttle body is junk; maybe something weird is going on with the computer. I dunno.

The CD player doesn't work and the only lights on the radio working is the screen. Anyone know where to get this radio cheaply? Or get this one fixed?

davester · September 12, 2018

When I cleaned the throttle-body on my '04 Sierra 3500 w 6.0, I moved the butterfly repeatedly, and cleaned both the body and the back of the butterfly, using TB cleaner and rags/small brushes. Never had any to do any kind of TB calibration and the engine ran ok (I did it as part of figuring out why my truck was running poorly, and I was doing intake & exhaust gaskets, upstream O2 sensors, knock sensors, MAF and MAP sensors, injectors and spark plugs).

As for the CD player, you might get one cheap off ebay, but you want to make sure it's not vin-locked. The radio's themselves, once installed in a truck, then become VIN-locked to that truck. The VIN can be cleared from the radio, but it's my understanding that it's primarily a dealer-only process to clear it so it's not cheap. 3rd parties may have figured out how to clear it and do it for less. You might be able to strip some parts from another used one to get yours working again.

Edited September 12, 2018 by davester

troverman · September 12, 2018

My engine runs well, it just has this super weird "wall" that the engine runs into at high RPM. Doing a pull in 1st gear it seems to wind up to 5k RPM without issue, but kicking down from top gear into 3rd or 2nd is normally where I run into trouble. At first I thought it was a tranny problem. But I can replicate this problem in Park...flooring the throttle only hits 3,000RPM. If I gently feather the throttle I can coax it right up to 6k RPM if I want. And sometimes it will pull just fine at WOT after a kick-down.

troverman · January 31, 2019

Another update. I'm using the truck for plowing this winter; it plow very well. With the cold weather, it seems that previous issue of hitting a "governor" at 3k RPM is gone. Now it revs fully. I replaced one axle seal but i still smell some gear oil. Nothing leaking though. Maybe not enough in it to leak! Who knows. Too cold now to check.