pala73

I have a 1997 K1500 P/U with about 88,000 miles..it's got the 4L60E transmission..I've always had trouble with that stupid 1870 code, the trans ran fine, but it always threw the 1870 code..I replaced some of the solenoids the fluid & filter and it went away for a while..It came back so I replaced fluid again with a high mileage trans fluid. The code did not go away this time. I've heard that it may be a problem with a worn valve and valve bore. The strange thing is that the trans now slips when it is very cold out = 20 F or less. As soon as it warms up to the 30s or 40s, it runs fine. Anyone know what the heck is going on here? I'd appreciate any help or suggestions.

MT-2500

Welcome to AF.
The valve body repair is only a band aid to the real problem on code 1870.
Transmission slippage aways go back to internal leakage problems.
Also morning sickness or slipping when cold.
Also high mileage fluid on a transmission that calls for dexron 111 fluid sometimes stirs up more problems.

I would just let it warm up a little before taking off and run it as long as still does good warmed up.

I am not much on additives on a good transmission.
But to help it along for some more miles Lucas makes a good transmission additive for a weak transmission.

If you are going to keep it a long time I would figure on a rebuild some day.

Good Luck
MT

__________________
Remember proper testing gives us the answer to many problems.
MT

pala73

Actually I was slightly mistaken..the code was 1860. I just changed the fluid and filter again today using regular Dex/Merc III and no additives. It runs and shifts great with no slipping, but I've only driven it once so far, so I guess I need to keep an eye on it for a while. I'm still getting the P1860 code, as well as P0740 now. What do these codes mean when they're together like that? Is it something with TTC circuit?

j cAT

this COULD be just a pump problem , have transmission shop check transmission pressures.....p0740 is tcc enable solenoid circuit this is wiring to transmission from pcm check connectors pcm feedback from tcc solenoid incorrect.....so if wires connector good then its in the tranny......

pala73

Suppose the seal between the tranny and transfer case was leaking? Would that effect the pressure? The old fluid seemed to be polluted by something when I changed it..I hope it wasn't gear oil..I haven't had a chance to check the trans case yet.

j cAT

usually coolant gets into the transmission fluid from radiator... what does transmission fluid look like? smell? if it looks like gear oil you have a bad transmission. clutch material from all that slippage....better get it checked out before more damage is done .....pressure as stated earlier is usually internal leakages by componets failing or bad contaminated fluid....transmission fluid is designed to produce pressure and operate at high temps.....if other materials/fluids get into transmission they will leave deposits that will kill transmission