Allison 5sp: Pulling out my GD hair

[jkholder09]

I have had worn out tailshaft bushings spin in the case.
Or the snap ring crack that holds the vss reluctor.
You will get brake messages, gear ratio codes and speedo issues.

If you pull the vss out of tcase you may see some metal particulate stuck to the magnet.
You may be able to liik into hole and check tone ring and inspect bushing.
Also that jumper harness with green and purple wires gets close the the front prop shaft.
Could it be chafing?

I apologize if this has already been checked I know we have been talking it over for a while.

 

[BigDMax05]

I'm just glad someone is throwing input out there. I need to look at the wiring harness all the way out but when the motor and tranny were out I had the tcase apart to check things out and the reluctor wheel looked fine. I changed the vss with another one I had and still same results. Also the bushing looked ok. I'm thinking this is a wire harness issue because it seems like when it warms up a little it goes away but when it gets below say 20* it starts acting up again. Maybe like a wire is broke or connection is bad and it makes up when it's warm. Again speculation but that's all I have for now. To be honest I've kinda given up on this for the moment because I have an LLY in for studs and gaskets.

 

[BigDMax05]

I finally narrowed it down to an nsbu problem. Either the switch I received from merchants has a problem or the wiring harness has a broken wire near the nsbu plugs. Dad had a spare nsbu he took off his truck so I swapped mine around tonight and now everything is fine at least for a minute.

 

[BigDMax05]

Update on this thread. I changed the nsbu plugs on harness with a merchant repair kit. Did not solve the problem. I am starting to think this may be a ground problem. I don't know.....does anyone know where I can find a good diagram for the ground system on the truck that actually shows where the ground attachments are at? I also noticed that the aftermarket radio would not shut off with the ignition and after I would power it off with the source button I could hear a hum through the speakers. So I pulled the radio and door chime module. I'm getting really tired of chasing my tail on this thing. Any help would be appreciated.

 

[BigDMax05]

Ok just pulled the TCM from the 03 that I'm having trouble with and put it in my 05 to see if it is a problem with the TCM. So far no problems. Gonna drive it all day tomorrow with that TCM in it and see what happens. GRRRRRRRRRRRRRRRR!

 

[ctjheiner]

Electrical stuff sucks @ss. I have similiar issues with my 04, but I haven't done any major builds like motor or tranny. I am looking for a ground schematic also, that would be extremely helpful. I checked the one under the drivers door, someone told me there is one from the motor to the body that I still need to track down and check. I found this thread:
http://www.duramaxdiesels.com/forum/...rument+cluster
I am going to check into finding a voltage regulator, that could be an issue on yours as well, will keep you posted.

 

[BigDMax05]

Electrical stuff sucks @ss. I have similiar issues with my 04, but I haven't done any major builds like motor or tranny. I am looking for a ground schematic also, that would be extremely helpful. I checked the one under the drivers door, someone told me there is one from the motor to the body that I still need to track down and check. I found this thread:
http://www.duramaxdiesels.com/forum/...rument+cluster
I am going to check into finding a voltage regulator, that could be an issue on yours as well, will keep you posted.

There is a ground point on front drivers side frame horn by the tow hook. Thanks for some help man! Btw also the tranny temp gauge goes either flatline or will bounce back and forth between 200 and 250 erratically and also I finally got some codes! p0700 and p0727 which is a code for the input speed sensor on the bell housing!

 

[jlawles2]

I use http://www.gmupfitter.com/files/media/photo/110/2005_LD_CKFullSizeElectrical.pdf for my electrical stuff. I think it does show ground locations.

There are several that I would check. Starting at the frame horn driver side. Then under driver door, and the one from the drivers head to the cab. Also there are 3 grounds on the driver side of the block and 2 on the passenger side (might be 3 on each side) that could cause issues.

 

[baddaddition]

Had the exact problems!!! I chased and chased wires. Spent a lot of useless money for two weeks only to find the wire from the TCM for the vss sensor had gotten pinched when motor and trans removed and installed a hundred times. I pulled the harness all the way loose up to TCM and removed the loom and check continuity from each end of every wire and got a really bad reading and ran it down to a broken wire. Casing wasn't damaged but had been pinched. Its frustrating I know. Just double and triple check yourself. There is also a possibility the TCM harness is chaffing on the power steering pump clamp. Keep us posted to what you find!! Good luck man!

Sent from a greasy hand under the hood of my buddys truck.

 

[prostreeter600]

I had a similar issue where I had dropped my transmission to rework the Convertor . Mine was that the large plug on the passenger side of transmission just in front of crossber was not pushed on all the way . Been running great since I pushed it together all the way .

 

[BigDMax05]

Had the exact problems!!! I chased and chased wires. Spent a lot of useless money for two weeks only to find the wire from the TCM for the vss sensor had gotten pinched when motor and trans removed and installed a hundred times. I pulled the harness all the way loose up to TCM and removed the loom and check continuity from each end of every wire and got a really bad reading and ran it down to a broken wire. Casing wasn't damaged but had been pinched. Its frustrating I know. Just double and triple check yourself. There is also a possibility the TCM harness is chaffing on the power steering pump clamp. Keep us posted to what you find!! Good luck man!

Sent from a greasy hand under the hood of my buddys truck.

I think if I can find one I'm just gonna replace the TCM-tranny harness. Throwing the 03 tcm in my 05 revealed the module is good. This thing just acts so erratic and doesn't seem to do the same problem twice. End result is always the same though the tranny is basically dead stick with 3rd and reverse. Sometimes just the speedometer and abs will quite working but then at some point the dash indicator will go away and the temp gauge will go haywire. Just gonna change out the harness. Hell I may buy a new one!

 

[BigDMax05]

Ok so it is still doing it with the TCM from my 05 in it. Also I have found out that whatever is happening is making the TCM lose power/signal completely. When it does it I can unplug the TCM completely and it makes no difference at all. I found a few relays under the hood in the fuse block to be turned 180* so that the terminals were in the wrong spot. For instance terminal 85 and 86 are the coil and 30 and 87 are the switched power but the relays were spun the wrong direction. How the hell this thing was doing anything right was beyond me. Grrrrrrr Gosh damn this thing is driving me nucking futs!

 

[jc1843]

You could add some temp grounds--just for testing.

Also have you replaced the ignition switch-?? That has caused strange problems on some trucks.

 

[BigDMax05]

No I have not changed the ignition switch. It needs a steering wheel clock spring and the bearing are noisy in the column so I was gonna try to find a complete column out of another truck to put in it and a new ignition switch from dealer. May try to add some extra grounds in next few days to see what that does.

 

[jc1843]

Replacing the ignition switch is easy-- just drop the lower column cover, pull the switch down [held in with plastic clips] have the key part tro "ON", and slip the new switch in-[should be indexed correctly as the new switch comes set to "ON"]. 10 minutes flat-!

 

[baddaddition]

I would venture to say it in the TCM harness. Have u pulled the trans pan off and inspected the wires from the 9 pin connector? Sometime also the pins in them damn connectors will release from the connector and back themselves out. So anytime u pull a connector apart make sure all them pins are pushed all the way in.

 

[BigDMax05]

I would venture to say it in the TCM harness. Have u pulled the trans pan off and inspected the wires from the 9 pin connector? Sometime also the pins in them damn connectors will release from the connector and back themselves out. So anytime u pull a connector apart make sure all them pins are pushed all the way in.

To update this thread I am still having this problem. I have found that whatever is going on it seems to lose power to the TCM and possibly the ABS module. I can unplug the connectors at the tcm and it will act the same. I am currently in need of a wiring diagram/pin out sheet for the truck side ECM/TCM harness. I walked away from this thing for awhile to clear my head of it for a minute. I have unplugged all the connectors from the bottom of the fuse block to check for loose or damaged pins and found nothing there. Im suspecting either a bad ground, or a damaged harness. still not quite sure though. Anyone have any good recommendations for the diagrams? thanks

 

[dirtracer347]

Check to make sure you have all of your speed sensors hooked up to the right sensor. I had similar problems as you and that was my issue. It's kind of stupid how there are so many plugs on the trans and t case that are the same connector. I had to find a diagram and check wire colors going to the correct sensor. They will all just about reach every sensor so it's easy to have them switched.

 

[BigDMax05]

Check to make sure you have all of your speed sensors hooked up to the right sensor. I had similar problems as you and that was my issue. It's kind of stupid how there are so many plugs on the trans and t case that are the same connector. I had to find a diagram and check wire colors going to the correct sensor. They will all just about reach every sensor so it's easy to have them switched.

I would think with that I would get a code? Not getting any sensor codes. Like I said up top I can unplug the TCM and it will act no different. I pulled the harness off of it and am going to try a new one. I'll post up once I get the new harness in it. Keeping my fingers crossed.

 

[dirtracer347]

I would think with that I would get a code? Not getting any sensor codes. Like I said up top I can unplug the TCM and it will act no different. I pulled the harness off of it and am going to try a new one. I'll post up once I get the new harness in it. Keeping my fingers crossed.

I got a code 1 time when I brake torqued it a little. I drove it a few times about a mile and moved it around the lot a bunch and never got a code. Only on brake torque.