Np 246 pinout?

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xDan

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Hey does anyone have the encoder motor pinout for the 246? 2003 if year matters. My tccm doesn't throw codes, the pushbutton control responds to shift requests, which is also evident on the tech 2 data page. Shees stuck in 4hi, and the only mode it goes to is 4wd auto, but the SUV always starts in 4hi. Really need a pinout... The only ones I'm finding are exploder or 243.
 

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That sounds like a bad encoder motor. On mine it would start in 2hi, I could switch it into 4x4 and the mode light would indicate that, but the Tech 2 showed actual was Auto. If you get to the decision that it's the motor, you can replace the resistance ring inside, or get a whole new motor. Pretty sure @Sam Harris and some others have done the fix instead of the full replacement.
 

Sam Harris

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That sounds like a bad encoder motor. On mine it would start in 2hi, I could switch it into 4x4 and the mode light would indicate that, but the Tech 2 showed actual was Auto. If you get to the decision that it's the motor, you can replace the resistance ring inside, or get a whole new motor. Pretty sure @Sam Harris and some others have done the fix instead of the full replacement.
Yup. Mine was acting strange for a couple years. It would randomly show the incorrect mode, even though it was in the expected 2wd mode. It also reported “SERVICE 4WD” fairly regularly, though a stop / start would typically clear that up. Sometimes she would refuse to go into the requested t-case mode, like 4hi, or auto.
Once I started her up and it showed in 4lo, and I couldn’t get it to change, I decided it was time to look into it further (again it was truly in 2wd, thankfully), so I was still able to drive fine. I changed the encoder ring, p/n: 88962315, after my Tech2 confirmed it was the problem. No trouble whatsoever since.. cheap replacement part, and the swap was easy.

It’s buried somewhere in the what did you do to your GMT800 thread. I suppose I really should have a build thread. It would make this kind of reference a lot easier.
 

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@TJ Baker has a post with pics:
 
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xDan

xDan

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Hmm, some colors are sure to match up, or that is at the TCCM? At the encoder motor on the tcase, it's an 8 pin connector utilizing 7 pins. RED, ORANGE, TAN and BLACK are 12 or 14 gauge, with a dark blue/white, brown/white and green/black 20 gauge wires. The connector pins and wires coming off the backshell are all good, with the right amount of dielectric grease in there. So the grn/blk is the reference voltage, and when disconnecting that plug and starting it up, probing that gives 3.95V and it drops off to low after 4WD codes trigger...I tried testing as per the 2002 and older method with it disconnected but I wasn't getting good voltage drops on anything really...maybe the TCCM is dropping it's signals when that is disconnected?

Anyways, I went into it further with the tech 2 and noticed the following:
Pulling the TREC CB and resetting the TCCM triggers three ATC codes:
C0306 - Motor A/B circuit malfunction
C0321 - Tcase lock circuit malf.
C0327 - Encoder circuit malf.
After erasing the codes, if it's in park, no 4WD codes trigger but in neutral, C0327 returns.

On the data screen I'm getting:
Encoder supply: 5.09V, and that holds steady ALWAYS
Encoder return: 4.08V, varies a little but good and stuck at the 4hi voltage, even during switch commands...so the encoder motor seems to be reporting the correct gear back to the TCCM (and it's definitely stuck in 4hi, I can hear the front driveshaft engaged as well as the front half shafts.
Mode switch return: 0.51V and during switch command delays or motor calls, that voltage stays constant. I'm unsure what this means, if that is normal or what?

In 4hi, it shows tcase lock disabled and when switched to auto 4wd, shows tcase lock enabled. Both modes show front axle requested as YES.

When going into the tcase function menu, all lights and button selections work, transfer case lock mode works.
When ATC motor A or B control is activated, I get this error: "Motor control attempted within 10 sec of previous control" no matter how long I wait. The tech 2 displays -50% motor load when turning ON either circuit, and -5% when selecting OFF.
Of note: When I trigger motor control, I can faintly hear the motor turning, with no grinding noise or clunks, until the error message displays.
I also, of course, inspected the two output shafts for play, leakage and damage but they are just fine. I also checked the fluid and it's a nice blue color at the fill hole. No sign of leakage anywhere on the tcase or trans either, just the engine rear main seal leak.

It's probably something in the encoder has gone bad IMO, as you all are saying, but with hearing the motor rotate and getting that error, could it possibly be the motor shaft is sheared off somewhere? It's too dark to pull the driveshaft and remove that encoder, I'll have to do it tomorrow. Let me know if after seeing all this info, if that just reaffirms the encoder motor or possibly something else? I wish this thing was a 241 or better yet, a 205! lol.
 
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Sam Harris

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I’d still expect it’s the encoder ring. Besides, it’s a cheap, fairly easy replacement. Be sure to let us know the result, either way. Keep us updated. And good luck.
 

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I’d still expect it’s the encoder ring. Besides, it’s a cheap, fairly easy replacement. Be sure to let us know the result, either way. Keep us updated. And good luck.

I tend to agree with this, since you're getting the lock circuit and motor codes for one. If you replace the entire encoder motor assembly, save the old one for a ring replacement. Wouldn't hurt to have a spare if that's all that's wrong with it. The encoder motor as a unit is the weak link.

It's curious, though, that the Auto setting is commanding the front diff actuator. I'm not sure that it should do that until the TCCM tells it to engage, and for that you need wheel speed differences. But I'm not sure, and I'll have to check into that next time I have the Tech 2 plugged in to mine. One thing you could do is remove the front diff actuator and see if it's engaging during both (actual, per the Tech 2) Auto and 4x4 modes. In Auto it absolutely shouldn't engage until the TCCM senses speed differences between the front and rear wheels.

It also wouldn't hurt to see if there are updated calibrations for the TCCM, although typically that module isn't the problem with this setup. For that you'd need TIS2000 to use with your Tech 2, or using the newer online check.
 

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One thing to add is that the diagrams in the link I posted don't necessarily apply to our pinouts, as you have correctly noted the 8-pin connector at the encoder motor. I have yet to find a wiring diagram that is for the 2003-2006 version of the encoder motor connector. AlldataDIY probably has it.
 

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