Allison 5sp: Wiring issues... need help.

[Jackblack99]

Ok.. a few weeks ago I had my transfer case harness come unhooked from the clips and fall into the front drive shaft and get ripped apart and pulled the wiring and plug out if the tcase shift motor..see pics below. The service 4wd light came on as well as the abs and brake lights..



I got kinda lucky and it actually just unplugged the plugs up in the engine bay instead of destroying them. So I get another harness and motor... install them and 4wd works now.. shifts as it should but the abs and brake lights still come on but only showed a code once and it was a C0055. It will shift into gear and not be in limp mode but when I let off the brake and the truck moves.. I get about 30ft range inhibited flashes on the DIC. I can switch gears and it goes away.. let's the truck move again for a short distance then says range inhibited again. No codes.. I've also got a female plug I can't seem to find where it hooks. Has to be a speed sensor because it's purple and green twisted pair like the rest of the speed sensors.. here's the plug




Thanks in advance for any help

 

[THEFERMANATOR]

Thats for the speed sensor in the rear of the transfer case. Some trucks have an extension harness that plugs into that one, and other end plugs into the speed sensor.

 

[Jackblack99]

I have a plug for the tcase output speed sensor and it'd already plugged in

 

[Jackblack99]

This is the 2nd harness I got.. it's exactly like the one I put in. The plug on the left hooks to the speed sensor on the tailshaft of the tcase. The one in the middle obviously goes to the shift motor and the one on the right is the female plug i can't find what hooks to it

 

[Jackblack99]

I have searched high and low, side to side looking for the spot it goes... don't see any broken plugs, missing or damaged wiring etc. Kind of at a loss as to where it goes..

 

[loganater]

you have a front and rear propshaft speed sensor, on my 04 the front wires to the connector are yel and ppl, the rear are lt blu and dk grn. sensor should be on top of the front output shaft. helm4-421

 

[loganater]

do you have a nvg
261

 

[Jackblack99]

Mine is an 03 with a 263xhd. I just double checked... there is no sensor on the front output on mine

 

[loganater]

yeah 263 does not have a front propshaft sensor, i got antother truck i can look on tomarrow with a 263

 

[THEFERMANATOR]

The plug on the left does not go to the output speed sensor if memory serves me correctly, the extension harness goes over the transfer case and hooks to the plug on the right. I'm pretty sure GM used the same harness for all the electric shift transfer cases, and just didn't use the plug on the left for the front output speed sensor on all of them. Your C0055 and range shift inhibited all point to no output speed sensor, and I'm betting it's because you don't have it hooked up correctly.

 

[Jackblack99]

I can't hook it up any other way.. the long plug on the right is a female plug.. my speed sensor on my tcase is also female. The male plug on the left plus into the output speed sensor on the tcase

 

[Jackblack99]

Unless I am missing something or misunderstanding what your saying

 

[THEFERMANATOR]

There is a seperate harness that plugs into the output speed sensor in the back of the transfer case that runs over to the frame, then that harness plugs into the one with a female plug end on it. I'm pretty sure you are missing a harness here. Let somebody with an 03 check, but the speed sensor plug right next to the shift motor plug was used on transfer cases with front propeller shaft speed sensors on all of them I have seen.

 

[Jackblack99]

Ah crap! I have a buddy locally that has an 03 with a manual shift tcase. I just didn't have chance to go look at it. Would it be the same? Thanks for the help.

 

[Awenta]

I'll climb under tomorrow if I get a chance and you don't get it figured out by then.

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[Jackblack99]

Thanks man. I'd appreciate it.

 

[Jackblack99]

Can someone get me a picture.. maybe a part number.. something for this extension harness that was mentioned above? I've searched and have come up with nothing. Maybe I'm not searching the right name or places.. just can't find anything. Thanks

 

[Awenta]

Can someone get me a picture.. maybe a part number.. something for this extension harness that was mentioned above? I've searched and have come up with nothing. Maybe I'm not searching the right name or places.. just can't find anything. Thanks

Sorry man, hectic day yesterday but I just got them. There's no extension you've got the right harness. That last plug goes across the top of the tcase and hooks in a plug coming out of the main Trans harness. The one that runs across the back of the Trans.

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[Awenta]

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[THEFERMANATOR]

So on earlier trucks they used an extension harness, on his that harness is the extension harness. The plug it hooks to at the rear of the trans is the trans output speed sensor plug for 2 wheel drive trucks. So hes sending the tccm a speed sensor signal, but nothing else.