PO746 CODE

[1DURAMAX]

I've been hanging around this forum for a couple of years now and found it to be a wealth of knowledge and information. I thank all of the member's for their posts, they have been invaluable. I've never needed to post before now
because I always found the info I was after, but now I need some info I can't seem to find. The other day I upgraded my Juice to the 125 Attitude and went out to play WOW NICE TOY. Then I set to no defuel on any shift,just once to try it. All shifts were slick until 4-5 then she slipped hard and set code po746 also went into limp mode. I parked it for a bit scanned with SNAP-ON MODIS.We couldn't clear the code but on re-start SES light was on and truck ran normal. Could some-one tell me what po746 is and how to erase code from history log. Thanks in advance.

[mdrag]

1DURAMAX,

I found this explanation for P0746 at THE OBDII PAGE (AUTOTAP) (http://www.obdii.com/codes.asp):

P0746 Pressure Control Solenoid A Performance or Stuck Off

I've never had a tranny DTC on my truck, but I imagine a TECH2 would be able to clear it - I'm not familiar with the Snap-On scan tools. The SES should clear after a number of ignition cycles.

[1DURAMAX]

Thanks MDRAG,
The SES light did go out after several ignition cycles. The SNAP-ON MODIS scanner had the same desciption as AUTOTAP but I was hoping I could find out what exactly it means. So that I can take corrective action if any is required.

[Modified]

Per Helms 2002, DTC P0746 was formerly DTC P1720.

Link below was question about P1720, which also occurred after Ally went limp. Probably overpowered the Allison with lack of defueling.
http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic;f=7;t=005723#000000


This is what I read, and don't know anything about it.

"DTC P1720 sets when the TCM detects an incorrect oncoming ratio, range to range, for an accumulated number of occurances".
This DTC indicates the on-coming clutch being controlled by Solenoid "A" is not applied or applied too slowly. This could indicate a leak or obstruction in a specific clutch or apply circuit. Check scan tool failure record for data for previous or current range information when the DTC was set to determine the specific shift when the DTC was set.
Important: Clutch failure due to installation of an engine power upgrade in not covered by Manufacturer Warranty. When engine HP or torque is increased over factory rating, a shift flare condition may occur.

Reference Helms 2002, page 7-874 and 7-783.

[1DURAMAX]

Thanks MODIFIED,
This explains what happened quite well. I'll go back in to get failure record data. I'm sure the transmission is OK, but its good to know what the DTC refers to.

FB

[dmaxalliTech]

Long story short, she slipped the clutches and likely put some black on em... Lets start talking trans upgrades now....

[heartbeatcanada]

Where abouts are you in Ontario????

[1DURAMAX]

dmaxalliTech,
Yeah I've already come to grips with the fact that I need some tranny up-grades, soon :( .more$$$$

heartbeatcanada,
I'm in Sutton. We met once at the Lindsay tractor-pulls. I was asking you about your hood. Heath at Hotrod Diesel was telling me your rig is performing most impressively smile.gif .

FB

[heartbeatcanada]

1duramax- Who's tranny are you going too???? Heath gonna look after you on that????

I remember talking to you last year at the pulls. Are you planning on pulling this year in the local class or street stock class????

[1DURAMAX]

heartbeatcanada,
Yeah,Heath is pricing out an ATS upgrade kit for me. The pulling is gonna have to wait for now. Blowing Rice-burners and Mustangs away is what do for fun right now. :D :eek: :D You pull alot from what I hear. What if anything has self-destructed so far? Pulling looks like its gotta strain the whole truck in a major way. :(

FB

[heartbeatcanada]

I haven't broke anything while pulling yet. This year might be different, now that i've got more hp than last year. The key is to keep your wheels spinning at the end and not bog the motor down so that energy has a place to go rather than through the drivetrain or elsewhere. Later Jeremy :cool: