DTC code 81

[Ricktinfwb]

having a shift problem on my '95 K1500 with a 6.5TD; code 81(2-3 shift solenoid circuit);
can anyone give me a clue?? Thanks

[Ricktinfwb]

Also, does this '95 K1500 even have a TCM(4L80E); my wiring diagram shows the tranny connecting straight to the ECM.

[DmaxMaverick]

The '95 doesn't have a "TCM". It's all in the PCM/ECM.

A solenoid error coupled with a real world issue (such as poor shifts) may be service related. It may be due for a fluid/filter change. Using synthetic ATF is the best thing you can do for the solenoids. If it's more prevalent during cold operation, the tranny needs a flush with the correct fluid grade, synthetic preferred.

[Ricktinfwb]

Thanks DMaxmaverick. & John C....I went through all your suggestions, and more....I think the problem was a canon-plug full of water/oil on the L/H side of the transmission, just above the shift-bracket mounting point....at least I hope that was it....so far so good!
Why am I not able to clear the code (81) by removing power to the ECM, and why would I not get the 1-2 (hand-shake) code upon checking the DTC's?
Thanks in advance....the help from you 'pros' is in-valuable!
Rick

[Ricktinfwb]

Well crap....back to the trouble-shooting....performed beautifully for an hour around town...4 starts (outside temps in the 50's) then on the last leg....no shift to 3rd!! And I still can't clear the code!
Help John C or DMax.......

[Ricktinfwb]

O.K. I got the '81' cleared by disconnecting both batteries for a few minutes...but still no '1-2' 'hand-shake' code when I read the codes....Any suggestions...maybe the ECM?




Thanks DMaxmaverick. & John C....I went through all your suggestions, and more....I think the problem was a canon-plug full of water/oil on the L/H side of the transmission, just above the shift-bracket mounting point....at least I hope that was it....so far so good!
Why am I not able to clear the code (81) by removing power to the ECM, and why would I not get the 1-2 (hand-shake) code upon checking the DTC's?
Thanks in advance....the help from you 'pros' is in-valuable!
Rick

[Ricktinfwb]

I cleared the codes by disconnecting both batteries for a few minutes...but still no 1-2 hand-shack code....my code 81 is intermittent, as is the shift problem; could it be the ECM?




O.K. I got the '81' cleared by disconnecting both batteries for a few minutes...but still no '1-2' 'hand-shake' code when I read the codes....Any suggestions...maybe the ECM?

[Ricktinfwb]

I cleared the codes by disconnecting both batteries for a few minutes...but still no 1-2 hand-shake code....my code 81 is intermittent, as is the shift problem; could it be the ECM? my Chilton book claims there should be a 1-2 code to indicate communication with the ECM.....

[DmaxMaverick]

my Chilton book claims there should be a 1-2 code to indicate communication with the ECM.....

The 1-2 code will flash to indicate a successful communication link, entering diagnostic mode, and there are no DTC's current, or in history. If you don't get the 1-2, either you haven't entered diagnostic mode, or you have DTC's.

[JohnC]

Shift solenoid issues and codes can often be traced to faulty transmission contacts in the ignition switch. They are often paired with erratic speedometer and tach indications and often first show up on cold days. You can monitor the voltage on the trans fuse. If it drops below about 9-10 volts when a shift is supposed to happen or during the power on self test you will get the code.