1990 Chevy K1500

[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...