Erratic line pressure

[DPC]

This trans is in an 02 4x4, suncoast converter and GMAC 5-3 kit. The trans was working fine until it ate the flex plate, (no alignment dowels). Flex plate replaced along with dowels. The trans will only shift sometimes and has the following codes

P0841
P1711
P1713

When I put a pressure gauge on it, it initially had zero pressure. Raise the RPMs and the psi will shoot up to around 210-220 and you can hear a whining sound, like a bad power steering pump. Sometimes the psi will hold and the truck will shift other times the psi drops and it won't do anything, most of the time no psi unless I raise the rpms.

All the shift solenoids are new along with the NSBU switch. I even swapped TCMs to rule that out. Checked all the normal stuff, grounds, fluid level, no leaks, etc. Thanks.

 

[Mike L.]

This trans is in an 02 4x4, suncoast converter and GMAC 5-3 kit. The trans was working fine until it ate the flex plate, (no alignment dowels). Flex plate replaced along with dowels. The trans will only shift sometimes and has the following codes

P0841
P1711
P1713

When I put a pressure gauge on it, it initially had zero pressure. Raise the RPMs and the psi will shoot up to around 210-220 and you can hear a whining sound, like a bad power steering pump. Sometimes the psi will hold and the truck will shift other times the psi drops and it won't do anything, most of the time no psi unless I raise the rpms.

All the shift solenoids are new along with the NSBU switch. I even swapped TCMs to rule that out. Checked all the normal stuff, grounds, fluid level, no leaks, etc. Thanks.

Fire the idiot that put it together. Your pump is probably trash.

 

[DPC]

Thanks, I will have it pulled and check the pump.

 

[DPC]

Ok, I have the pump out what am I looking for to tell if it is bad? The separator plate has some wear marks on it and so do the gears.

 

[Mike L.]

Ok, I have the pump out what am I looking for to tell if it is bad? The separator plate has some wear marks on it and so do the gears.

Post a picture of the pump and sump filter element.

 

[DPC]

Pics.

 

[DPC]

The filter was new.

 

[juddski88]

Cut the filter open at the seam and unfold the element to check for debris.

 

[DIESELMAFIAPER.LB7]

Who built it?

 

[Mike L.]

The pump shows a lot of wear and I would not use it. That could be the cause of your noise but it shouldn't cause the pressure problem you are having from what I see. Check for rips in both bell housing gaskets also.

 

[DPC]

I will check the gaskets, the sump filter looked clean inside. I have new pump on the way. Anything else I need to check while I have it apart? Thanks.

 

[DPC]

Who built it?

I built it for a friend of mine, but he installed it. Not sure why he took the alignment dowels out. That is what started this whole mess.

 

[juddski88]

I had a brand new filter cause loss of pressure this weekend on a new build but only when the fluid was hot, and during all operation it would flare shifts etc. Took about 10 miles to finally get bad enough that it lost all suction...swapped in another filter and it shifted like butter! Just one of a few new ones for the notebook this weekend!

 

[mtl_dmax]

I had a brand new filter cause loss of pressure this weekend on a new build but only when the fluid was hot, and during all operation it would flare shifts etc. Took about 10 miles to finally get bad enough that it lost all suction...swapped in another filter and it shifted like butter! Just one of a few new ones for the notebook this weekend!

Wow, good find on that one......it would have taken me a while to suspect a brand new part being bad.

 

[Evan@InglewoodTrans]

Wow, good find on that one......it would have taken me a while to suspect a brand new part being bad.

Only so many things can cause low pressure and the internal filter is the simplest and easiest place to start. It's not uncommon for brand new parts to be bad and internal filters are one of them.

 

[mtl_dmax]

Only so many things can cause low pressure and the internal filter is the simplest and easiest place to start. It's not uncommon for brand new parts to be bad and internal filters are one of them.

Duly noted......much appreciated.

 

[DPC]

It will certainly get new filters when I put it back in.


Sent from my iPhone using Tapatalk

 

[juddski88]

Wow, good find on that one......it would have taken me a while to suspect a brand new part being bad.

Well it wasn't difficult on this one because it was a brand new pump...yup, I had a stock 6sp with a shattered pump drive gear...pretty cool...but it was crazy because the last time I had a bad filter was 2 yrs ago on my own trans and it didnt build enough pressure right after the install to even engage at all. Thought I had done something wrong. This one was slightly different in it's symptoms.

 

[DPC]

P1713

New pump, new filter, line pressure problem solved.

Now I have a P1713 (Trans pressure switch, reverse circuit) problem. When I put it in reverse it commands reverse and then 1-2 seconds later it actually goes into reverse and the shift indicator starts flashing. Shift into drive and it goes straight to third (limp I assume).

I can clear the codes while in park vehicle running, for a split second I can hear a whine, pressure gauge flicks, and code comes back. Pressure switch bad??? Thanks.

 

[Mike L.]

Check the o ring on your pressure switch manifold. It will be the one all by itself on the end.