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My New to me K-2500...

checked the vacuum lines and no visible cracks, the wastegate solenoid is hard to move at an idle, the lift pump seems to be working fine. went for a longer drive after clearning the codes to see what might come up. Now I have the following codes.

33 44 45 48 87. so changing the baro sensor added code 33 which suggests low vacuum, the sensor we put in is a ACDELCO Part # 2131545 (the one on the firewall). wondering if this is actually the map sensor on my truck, but this has a vacuum port and my current map sensor does not have a vacuum port. 48 seems to point to the IAT sensor, and code 87 is transmission, changing the trans fluid this week when the filter kit comes in... distributor had no stock for them.
 
sometimes the waste gate can get carboned up and not seal properly and cause low boost, especially from a nonworking system. try disconnecting the linkage on the wastegate and work it back and forth trying to slam it shut and break loose the carbon.
 
With a "F" code engine there is no vacuum hose going to the firewall mounted baro sensor. On "S" engines there is.
Something your code have in common is they share the same 5 volt referance signal from the ecm. Check for 5 volts or close to it at the baro sensor gray wire and ground. They also share the same sensor ground through the ecm. Check grounds at the rear of the intake manifold. There should be a single large black[10 or 12 gauge wire] and another with small black and a tan wire on the same ring terminal. Take both loose and clean very thoroughly. These are the two main grounds for the tranny and ecm.
 
took a long break from working on the truck over the spring/summer. finally found some more steel rims for it, shot them black, and changed the tires for some that have some tread. changed the pass side caliper since the original one locked solid (smoke coming off of it). Still havent sorted out the issues with the vacuum, I am thinking it may actually be the pump itself, I picked up one of the vacuum tester/brake bleeder combo vacuum pumps figure this should work for test the system. I should also mention the other day when driving the truck I was going down the road fine, then all of a sudden no power, almost like the trans slipped completely or engine died, then all of a sudden cut back in dang near snapped my neck and lots of black smoke.. smoked out 4 lanes of traffic. So now I am really thinking something with the vacuum system or the injection pump or pmd. (I have spare pmd's). also the abs light is on, so I have to track down the bad sensor/wire or bearing yet. (unless there is a open recall yet from GM haven't checked for any open campaigns yet). whats the best way to check the vacuum pump with the style tester/pump I have...
 
well went ahead this week and worked on the truck more, ended up putting new front calipers, brake hoses, and wheel bearing on the driver side. new caliper and hose on the passanger side, and I have to replace the abs sesnsor yet. I have the part just haven't gotten to it yet. put new gm plastic vacuum lines on and I am still tripping codes, but also noticed tonight the truck has a seized brake on the rear, now for the fun, someone I assume has put a rear disc brake conversion on the truck since it has rear disc brakes. (I didnt think k2500 8 bolt trucks came with an option for rear disc) I guess next question is how do I identify who makes the caliper so I can either get a replacement or the seal kit to rebuild it, and also since I am there and doing that anyways make sense to just change out the brake hoses on the rear, and lube up all of the parking brake cables to make sure that is not the source of the rear brake seizing. another thing I noticed is that sometimes when I start the truck when hot that the check gauges light is on with the left signal light and the glow plug light I am assuming a bad ground but can anyone else pipe in as to what may cause that?
 
Did some research today and by the casting numbers on the calipers the rearend has likely been changed to a 1999-2001 2500 silverado, or suburban with rear disc brakes. I will confirm that when I tare it all apart... now I am hoping that they matched the gear ratio in the rear end, since the diff cover is leaking anyways time to do a service so I will count the gears in the rearend, and then I can find out how many splines the axles are and if they are semi floater or full floaters. :) this has really turned into a project truck now just to get everything fixed on it.
 
Hard to tell from your first photo, but it appears to be a semi-floater since we can see the rear-most lugs at that angle. There should be the end of the axle sticking through if it's a full floater.
 
thats what I thought as well, but wasnt sure with the upgraded disc brakes/rearend and I have a buddy who argues that 2500 8 lugs should have been a full floater, but I think he is smoking some good stuff. I thought full floater were more for the 3500 SRW and the DRW, or the 3500HD cab and chasis.
 
okay, well the truck is a 8600LB gvw, and has 8 leafs, but of course with the rearend being changed out looks like it might be a light duty 8 bolt rearend with the rest of the truck being a heavy duty. find out more later today when I pull the diff cover.
 
WOW, 8 leafs?? I'll bet it rides like a log wagon.

Can't tell if FF or SF by the GVW. Our family has a K3500 with a semi-floating rear axle. Maybe uncommon, but they're out there.
 
well took it all apart, the park brake's were screwed got them freed up and released, calipers were okay, 4.10 gears in the rear end, semi floater axles. put some new axle seals in, diff fluid with the posi additive, now to figure out what is in the front, otherwise I may be looking for a different diff. debating actually about doing a solid axle swap on the front yet. talked to a buddy who scraps trucks and he has some 8 bolt rims/tires/center caps and beauty rings for me from a 8 lug diesel burb that he is scrapping on tuesday. I seem to have a broken abs wire yet on the front pass wheel, need to fix that, also noticed when you put this thing in reverse it is shaking the truck and sometimes when you first put in drive and give it some fuel... The trans fluid smells completely burnt, this only happened in the last little bit since the brakes were all seized... so I am thinking and fluid/filter service on the trans, otherwise clutch packs could be going on it. I am still tripping codes for egr, and boost, this is a non egr truck though... New Vacuum lines, and I am reading 15 hg at the actuater and at the boost solenoid. need to check the vacuum pump yet..... running out of ideas as to why I am tripping codes for egr and boost...
 
okay, so I scored some newer alloy style wheels for $200 with tires, there mounted on the truck now. I did grab the other 8 bolt wheels from the burb, but they are the older style for the drum brakes. Turns out the burb was a 95 4x4... so computer from the burb is now in my truck. No more check engine light, but it stumbles or surges at around 1000-1100 rpm if you tap the fuel while in park. it just kinda revs up and down at that rpm, also noticed it doing it around 1400-1500 if I hit the high idle switch and tap the fuel.... I am thinking that it is either the PMD Starting to go, or the injection pump is out of time. The injection pump was replaced on this truck by someone I suspect trying to solve another issue (maybe the check engine light). The guy with the burb is going to remove the front and rear diffs from it (full floater on the rear), they are a matched 3.73 gears for the front and rear, and he is also has the trans from the burb, it was rebuilt 10K ago aparently when the burb also recieved a gm goodrench crate engine. (he is keeping the engine for his tow truck). getting both diffs, and the trans for $400. I resold the rims from the burb to a bud that had some stolen from an old crew cab that is in storage and needed something to put on it. oh and sorry guys finally re-read my earlier post, yup 8 leafs I was smoking some good stuff that night apparently or it was a typo, it has 5 leafs with the 5th one being double thick, still rides like a buck board compared to the 1 ton though. (same amount of leafs). but at the point now where I have to get this 2500 running, the 93 1 ton is starting to get up there on the temps constantly and the intake is dumping into the coolant on that truck, but I need this one running before I can really stop driving the 1 ton. So anyone got any ideas on the surging it is doing?? (if i put the old computer it, it no longer does this put has the check engine light issue).
 
oh forgot to mention also all of a sudden my volt meter is sitting around 9.5-10 volt and my tach basically sits at 5-600 it dosnt move from that spot no matter what you do any ideas on this as well? (found I had a broken charge line from the alt to the battery so I fixed that tonight (crimped a new end on). But that didnt resolve the tach or the volt meter issue.
 
SnowDrift said:
Rear disc? Nice!

Exact same interior as mine. Maroon leather in a red truck makes no sense to me, but it is what it is.
Click to expand...
Same on my 1994 K3500 Chevrolet Crew cab single rear wheels.

Since I backed into the tree, I have a maroon tailgate to go with my interior. The Maroon tailgate looks a lot better than the state truck orange tailgate I had on there for a while.
 
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