1990 Chevy K1500

[Second Series]

1990 Chevy K1500. Basically the same set up, 5.7 V8, 5LM60 5-speed transmission. Shortbed stepside, I’m comfortable with ½ yard of gravel so this is big enough for that although I do like the full size bed of the GMC for plywood and sheetrock.
33” tires! Looks good, but a stiff ride probably due to the torsion bars were cranked up so the fronts would clear. This originally had A/C and I’d like to put it back, the compressor was replaced with a pulley. I’m not a fan of led lights, but it has led lights on all four corners. I might be able to use the rear fixtures from the GMC when I part it out. The fronts are completely different with four headlights where the GMC has two.
I purchased this truck last month and drove it home. It runs well, I like it and my son is eager to ride. The check engine light is on and the check gauges light is on. The temp and oil gauges fluctuate. I ran a check on the codes and got 43 Electronic Spark Control (ESC) circuit. I’ve been reading up on that and will start by checking the resistance of the knock sensor. I’ll remove the gauge cluster and check the contacts in the connector to try to fix the gauge issue. The brake light is on and the parking brake cable is saggy. I’ll look into the cable first and go from there. A good driver/project.

[Second Series]

Here's my other truck: http://67-72chevytrucks.com/vboard/s...d.php?t=786383
At first I was going to just have one thread on both truck, but decided to have two separate threads.

I crawled under and found the knock sensor just above the oilpan in front of the starter. I pulled the wire and checked the sensor with an ohmmeter. 3.9k is what it measured, so that’s good. I put the wire back on and went to the top. I used this diagram to help locate the ESC Electronic Spark Control.

I removed the connector from the ESC and measured the Blue wire with the ohmmeter, it read .6Ω, not good. After fiddling about awhile, I went back under and pulled the connector off the knock sensor again and the wire measured open as it should. I put the wire back on the knock sensor and measured the end by the ESC and now it was at 3.9kΩ. I should mention that when I first pulled the connector off the knock sensor, I noticed the center part of the sensor was loose. So it looks like there is an intermittent short, probably the knock sensor.

Looking at the picture I took, I can see where the center part has a crack. I could probably put some high temp glue on it and be good for now. I’ll clear the codes and run it awhile and see if it throws any codes. So far it looks like a simple fix. I have read about problems directly and indirectly related to the knock sensor that can cause a code 43. I don’t want to throw parts at it, instead I’m trying to figure out how things work and determine the problem.

[Second Series]

I Put the rear on jack stands and determined the passenger side brake cable was seized. I replaced that and now the parking brake holds. The brake light is on and I get a code 3 “Open Dump Valve or ECU Malfunction”. I’m not sure how to proceed on this, I disconnected the battery to clear the codes, but the brake warning light remains on.
I put some epoxy on the knock sensor and gave it a day to cure. I was poking around underneath and touched the battery wire at the starter. The stud in the solenoid is loose, I can rotate the wire, stud and nut together. The truck starts fine, but it will be a problem on the side of the road. I also noticed a wire on the driver’s side coming from between the rotor and backing plate. It looks like a ’95-up ABS rotor was installed…
I’ve been reading about the RWAL system and the brake warning light, Next thing is to ohm out the connector to the dump valve, when I get some time.
I want to drive this truck, so I filled up the gas tank and got a load of gravel. The bed went low with ½ yard, my ¾ ton truck handled the weight better, but at least I wasn’t rubbing the 33” tires on this K1500. I pulled my flatbed trailer out of the bushes and went for a drive. The K2500 is partly dismantled and I loaded up the longbed, front clip, hood and bumpers. The scrap yard is paying 1 cent a pound, so maybe $10.00 for these truck parts. I decided to keep them and make an art fence. That bed floor would make a nice shed roof, I couldn’t buy corrugated tin at that price. I’ll put an ad up before I get out the torch…
No more check engine or check gauges light and no fluctuating temp and oil gauges. I hope the shorted knock sensor was all that was the problem, only one way to find out, drive! The truck didn’t come with door keys, so I bought a pair of door lock cylinders, when I get time…

[Second Series]

It’s been awhile since I updated this. I replaced the lock cylinders. I don’t remember if I replaced the starter, but probably. I was trying to find a good cheap rack to haul lumber. I could not find one narrow enough for the stepside bed. I did locate a shortbed rack for $150, the price was right so I bought it. We set 2x4’s across my bed and set the rack on that to get it home. I cut the rack rails to fit my bed, and welded with Oxy-Acetylene. I located some kind of nut sert to bolt it to the bed rail. It works well. I have been using this truck for weekend projects since I picked it up a year ago. I decided to drive it to work last week and it started shifting hard on the way home. Grinding when going into reverse, and hard to shift forward gears. Last weekend I checked out the clutch hydraulics. I found no sign of leaks. Dirty fluid, I changed the fluid, and attempted to bleed the clutch system by placing a cinderblock on the pedal and cycling the bleeder valve, I did this several times. That didn’t fix it. I was able to press the clutch, start the truck and release the clutch to move. I drove it to the shop in 1st gear, it would not shift with the engine running. The stick didn’t feel sloppy, so I think that connection is o.k. I had read about a pin breaking where the stick attaches on top. I also read about the pilot bushing binding causing the input shaft to spin. The one post I read about the pilot bushing turned out that replacing it did not fix the issue. This is a 1990, so the transmission is probably a 5LM60. The guy I got it from said he replaced all the fluids, I wonder if something other than GM synchromesh fluid was put in the transmission? It’s been at the shop for a week, still waiting to hear back. They tried bleeding the system with no change.

[Second Series]

Looks like it needs a new clutch...

[LT7A]

Howdy neighbor, that's a neat truck.

[Second Series]

Thanks LT7A! New clutch and u-joints it's back on the road. They also replaced the starter, I couldn't remember if I had done that after I found the loose connection, stripped stud. I noticed the 4x4 light would illuminate for a minute after starting in 2WD. I tried to remove the transfercase switch, but I couldn't get it to budge.While trying to figure that out I did finally connect a ground strap to the engine that was hanging free. That may have been the intermittent gauge fluctuating issue, I won't know until it doesn't happen again. I'm back from vacation and drove the truck a couple times. It hasn't been shifted into 4WD, and the 4x4 light hasn't come on, so it may be a faulty T-case switch. All I can do is drive.

[Second Series]

It's been awhile since I updated this… I swapped out the T-case switch twice. The first one I bought was faulty. I took an ohm meter to the parts store when I got the second one to make sure it functioned correctly. The parking brake wasn’t great, and so I decided to relace the driver side and the front cable. I found six different cable lengths for the various truck configurations, so I made sure I got the right parts for this truck. Now it is good and tight. I had purchased an R-134 compressor and lines from the pick it yard. When it was in the shop for the clutch I asked them to install and get the AC working. They gave me all the parts back and said it was originally R-12 and it would need some other parts. They suggested I hook everything up and they could take it from there. Wow, that was a year ago. I picked up an R-12 compressor from the pick it yard. Then I discovered how scarce R-12 is. I found some on C-list with a machine, so I picked up this shop fixture, way overkill, but now I can do whatever on A/C systems. It was $100 so the price was right. I have been reading up on R-12 vs. R-134 and could go either way. I’ll restore the R-12 system on this truck, and build the R-134 system on my other truck.

[LT7A]

$100 for the dials and a free blue cabinet. Cool!