OBD-1 code 81

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#11

04-28-2020, 07:58 AM

cavecookie

Beginning Member

Thread Starter

Join Date: Jul 2011

Location: Central Oregon

Posts: 20

Quote:

Originally Posted by KnightBlazer

Any Luck? I'm not sure about any external grounds. I just looked in my ATSG Manual. . .for 2nd and 3rd it only lists the 1-2 Shift Solenoid and/or circuit, or Sediment as possible causes. When was the last time the trans was serviced?

Sounds like you need to just drop the pan, if you haven't already. My valve body wiring harness was pretty nasty and disintegrating when I opened mine up, so that could be the problem as well.

I don't think I saw error ask. . .was there anything that happened leading up to the problem? Any work done recently before it started?

Here is a link to the Rebuild Manual error_401 gave to me when I was working on my trans.
https://drive.google.com/file/d/14ho...ew?usp=sharing
The Valve Body section that starts on pg 133 is prob what you'd want to look at. There's a tech bulletin on pg 143 that gives you the resistance for each solenoid, and tells you which pins on the harness connector go to each solenoid.

Well, no luck finding an external ground. I was actually doing some work on my Blazer when the trouble started. I replaced the FPR inside the intake plenum, and also discovered that my battery was weak, and not giving me 12 volts, so I replaced that, as well. I wonder if that low volt situation could have anything to do with the trans problem. Anyway, I have a new solenoid kit ready to install this weekend, including a new harness...I have delayed dropping the pan until I have exhausted all external options. Something odd happened about a week ago, though. For 2 days, the tranny worked normally, but now I'm back to limp mode, so fingers crossed that the solenoid kit solves the issue. Thanks a million for the link, that is going to be a big help!

Last edited by cavecookie; 04-28-2020 at 08:00 AM. Reason: added content

#12

04-28-2020, 08:07 AM

KnightBlazer

Junior Member

Join Date: May 2017

Location: Tampa Bay, FL

Posts: 255

I suppose its possible the low voltage caused problems, but from what you describe I doubt that's your issue.

If it worked again briefly then it sounds like there is either a bad/loose connection, failing solenoid, or sediment in the fluid. Hope the new parts fix it for you.

Assuming you know, but make sure to get fresh ATF, filter, and pan gasket when you put it back together. Make sure to get the old filter seal out, and the new one seated fully, along with the filter. If the old fluid is really dirty, it would also be a good idea to disconnect and flush out the trans cooler lines while you're at it. Good Luck!!

#13

04-28-2020, 08:18 AM

cavecookie

Beginning Member

Thread Starter

Join Date: Jul 2011

Location: Central Oregon

Posts: 20

Yep, I also have a new filter and gasket, and will pick up about 6 Qts of ATF. I have also been taking advantage of internet sources to make sure I don't run into any nasty surprises in the middle of the project. Can't really have the vehicle down for any length of time, it's my daily driver! I will update when the new parts are installed. I agree, I think when I open up the tranny, I will find some bad wiring, the fact that it worked for a couple of days leads me to think I have a bad connection somewhere, causing the intermittent issue.