I'll just get to the point.

95 Chevy K3500 6.5 Turbo
Codes 39, 68, 85 & 87. What are they? Book tells nothing of these codes. & my trans if not wanting to shift into overdrive, I'm changing the filter & fluid, & hope it helps. Please, this is my ONLY transportation. Thanks!!!

Joe

Welcome to the 'Place, joe.......

First thing you need to do is address 39 - it can cause the other codes - pull your brake pedal up against the stop, that code should go away - that code is the brake switch\TCC switch, prolly will need to replace it.

68, 85, 87 are codes indicating PCM is measuring excess slipping in the gear ranges - you should also disconnect the connectors at the transmission, check them for dirty\oxidized\corroded - clean'em and plug'em back in.

Thanks, I'll try those. Now, I've talked to guys at work & one said something about a electronic component above the Shift linkage could be bad. It's a 4L80E btw. The part has 2 connectors on it & is kinda rectangular. Now it seams to work fine when cold, but after warmed up it starts to act up & 4th gear will not engage, but the other 3 gears are working just fine. Now I told him what was going on & he told me about that electronic part & told me that it would produce problems like I've got. Is this true?

Joe

My '93 did exactly that when warmed up, i replaced the 2-3 shift solinoid and PWD unit in the trans. Worked fine after that, cost about $60 more or less a buck.
Don

Dunno, Joe - sounds like he's referring to the shift quadrant switch, tells PCM which range is selected, Neutral safety switch, and backup lites.

There is a connected two-wire speed sensor at the front, another unconnected at the back, and another connected in the xfer case - pull the two connectors, check them and plug'em back in.

Pull both connectors in the quadrant switch, same routine

Pull the large multi-wire connector on the side at the rear, same routine.

That's a good fix, Don, but I think the brake switch should fix most of this one, tho.

Well I replaced the brake light switch & checked the wiring, help some, but still have the problem. It's not as bad & the truck seams to want to fight the problem a little bit, it takes longer for the trans to stop shifting past 2nd gear, it if does it at all. I'm going to change the fluid again & see if that helps, I'm also going to try & get it into a shop to have it looked at.

Joe

not worth changing the fluid if yer gonna put it in the shop unless it smells burnt or has an off color. better to wait for the results then change the fluid. ED

Well, trucks been to the shop, bad news, the clutches are burned up & slipping bad, being an 4L80E electronics Trany, the ECM is picking up on the slipping & shuting off the 3rd & 4th gear solinoid. :mad: But I'm working on trying to get a replacement trans right now, so hopefully I won't be down for long.

Joe