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Code 59 and 81????

Michaeljp86

Michaeljp86

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I checked my truck today, the one that wont shift. The 2 codes I got were 59 and 81. I have a blown rear brake line so thats probably caused 81 I think.

I looked up the coded with a google search and came up with DTC - 59 Trans fluid temp sensor circuit error (high voltage)

Is that what code 59 is for the diesel trucks? The website said it was for EFI trucks.
 
According to my manual you are right on the code 59 but the code 81 is: trans 2-3 shift sol circuit. Leo
 
I honestly don't know, they could be good and are reporting a problem or they could be the problem. I know nothing about auto tranny's. Leo
 
Back at the "Place" there is a member called "GenBiltstein". I would send him a PM. From what I have heard he's your man. Leo
 
Did it set the codes first thing after you cranked the truck? Has the truck been setting up for a week or so? Check the fluid level. Clear the codes and see what comes back.

I see these two codes show up together all the time on HMMWV's with new transmissions, it happens on its first 2-3 upshift because the clutch piston is empty causing a slight slip. The TCM see's the slip, sets the code and usually puts you in limp mode(stuck in 2nd gear).

The 59 is fluid temp, dont know why it occurs with the 81 as mentioned, unless the computer is thinking the fluid is hotter(thinner) than it is seeing from the sensor causing the slip.

I'd ohm the 2-3 solenoid and temp sesnor, check the big plug on the side of the trans all these wires run through that plug.

HTH,
 
The truck has been sitting all winter but had the trans problem last year. Tomorrow I'll clear the codes and drive it.

How do I know what to test one that plug?
 
You said it has been sitting. Have you checked for leak, sometimes truck that has been sitting causes the trans to leak hence low fluid. When did you changed the fluid last time? or even check the level?
 
midniteplowboyy said:
I'd ohm the 2-3 solenoid and temp sesnor, check the big plug on the side of the trans all these wires run through that plug.

HTH,
Click to expand...

Just saw this here

get it warm, just drive it a little then try pulling off the transmission computer harness from tranny and check resistance across pins E and B on the tranny, there is a red wire going into E and a green wire going into B. There should be between 20 and 40 ohms of resistance. I recommend using a digital multimeter. If the resistance is wrong it would explain the PCM seeing funky voltages and set the 81 keeping you in 2nd only

L and M on the tranny is the temp sensor, I'm thinking it should be 1500-3500ohms, but I dont have specifics for that variable resistor.
 
Is the pedal thing stuff for OBD? You have pre-OBD, I dont know how that works for clearing codes. Usually if you leave battery off for 15 minutes it would clear codes.

Otherwise, with it in diagnostic mode try doing both pedals at the same time for 15 seconds, let them up, and put them both back down again for 15 seconds, then turn key off, and back to ON without cranking. Are codes gone then, and then do they come back on first crank?
 
buddy said:
Otherwise, with it in diagnostic mode try doing both pedals at the same time for 15 seconds, let them up, and put them both back down again for 15 seconds, then turn key off, and back to ON without cranking. Are codes gone then, and then do they come back on first crank?
Click to expand...

Thats what I did, I tried it 4 times and it never cleared the codes.

I checked the ohms on pin E and B, I have a yellow wire instead of green. I got 21.6 ohms.

I checked L and M too but cant remember what I had. 16 something I think.

I checked the fluid again and its still fine.
 
The solenoid sounds good then. Wire colors must have changed with years and PCM type, but tranny is the same and the signals should be.

And I guess you should check that the reference voltages are coming from the tranny computer. It should come in to pin E, but I dont have my manual now for what it should be or any others. Will get back to you tonight if someone else hasnt advised.
 
It only takes a few seconds to clear the codes by unplugging the Batt's/TCM. You may be able to clear the codes by pulling the TCM fuse, I haven't tried, I use my scanner on my truck. On the HMMWV's I just unplug the TCM itself.

Clear the codes again, let the truck idle for a few minutes/dont drive, does the codes show up again? With codes clear, put trans selector in 2nd, go for a drive, do you have first and second, you should not have any codes?

I'd ohm the involved wires to the TCM not trans/case connector. If they ohm good, splice a wire into the 2-3 solenoid wire(if tech scanner is not available), turn key to run, ground your 2-3 wire, you should hear a click in the trans pan when you tap that wire to ground. If it clicks, take it for a drive with truck in OD/D, you should have first and 2nd, if it dont shift to third/sets check engine light, ground that wire, does it shift to third, does it slip?

Most any old scanner will talk to the TCM if you have a friend that has one, you only need a TechI/II if you want to manually shift/control line pressure.
 
With the IGN ON, engine OFF, check that the harness (not tranny) at pin L has 3.5V and M is Grounded

On my 94, E gets its power from the IGN switch, 12V, and is fused on TRAN fuse, check that fuse that it has continuity.

If you want to idle the engine and check it while its plugged in, if you have a safe way to do that, by poking into the insulation of the other side of the 2-3 solenoid, the wire that went to pin B there should be 0.4V.
 
buddy said:
With the IGN ON, engine OFF, check that the harness (not tranny) at pin L has 3.5V and M is Grounded

On my 94, E gets its power from the IGN switch, 12V, and is fused on TRAN fuse, check that fuse that it has continuity.

If you want to idle the engine and check it while its plugged in, if you have a safe way to do that, by poking into the insulation of the other side of the 2-3 solenoid, the wire that went to pin B there should be 0.4V.
Click to expand...

I pulled the ECM fuse and it didnt clear the codes. I got the batteries unhooked so Ill try that.

I checked pin E and get 12v and M is grounded. But on pin L I dont get 3.5V I get 5.01V.
 
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