A 'Hiccup' with an AutoShift

A 'Hiccup' with an AutoShift

A 'hiccup' with an AutoShift

Brewen
07 December 2009
12:05 PM
Howdy all,

A little story...to perhaps brighten your day.....

One day, not so long ago, I climbed into our truck (see sig) to get hooked up to go.  I turned the key on, waited for the "N" in the dash display and fired it up.  The truck started fine, but when I tried to shift our AS2 into drive, nothing happened.  It was not until then that I noticed the red "SERVICE" light was on solid, and even though I punched buttons, nothing would happen.

I shut it off, tried it again, truck started okay, but the service light continued to shine unmercifully!  So I got out the tranny book and had a look, nothing there on this particular problem, so I called the Eaton/Fuller hot line and explained the problem.

They suggested: 1: Clean all the battery connections FIRST, and try it again, if that didn't work, disconnect the shifter control unit itself from the plug at the back of the unit, leave it for 15-20 minutes to see if it would reset itself and then plug it back in again.

So, I did these things and it still wouldn't work.  Fiddled and diddled around some more and nothing seemed to make any difference, so I called Eaton/Fuller back.  They then suggested it was "probably" the shifter control unit itself, that it sounded like it was not 'powering up' correctly and that this was usually a sign that the controller had failed.

Now, at the time, we were in a CG in a very large, strange city, a very long tow job away from the nearest Volvo dealer, so I was a bit reluctant to go that route.  I called the Volvo service guys and had a very nice chat with them and basically got the same opinion, that the shifter control had failed.  Well, it's not a difficult job to change it, so, transferred to the parts department (luckily I had remembered to take my heart meds!) I asked the price of a new shift controller.

Yep, I ordered one of these $1500 +/- parts and had them bring it in the next day.  When it showed up, I took it out to the truck to install it, and, of course, just thought I'd try the key again, just to see what would happen?  You got it!!  Fired right up, no service light, shifted into drive just fine, back to neutral, into reverse etc. etc. etc.  Shut it down, turned it on, everything worked just fine!! GRRRRRR!

So I called the Volvo dealer, 15% charge for returning the part!!  Hmmmm, put the new one in?  Or ???  After due consideration, opted for the return and 15% charge (tranny is still working fine at this point...) and the next day we were on the way south.

A week later, in Northern Cal, the tranny had been working just fine, no more hiccups.  Got up in the morning, packed up to go, went out to the truck, you got it!!  The "service" light was back on again!  Went through all the steps again, and half an hour later, it was fine and working again and we were on the road.  But so far I still had not been able to figure out just which one of the "steps" was fixing the problem.

TWO weeks later (with no recurrences) we were in Quartzsite and thinking about leaving.  So, one morning I thought "better check it", which I did, and no 'service' light, started, shifted etc. just fine.  Great!! Okay to go tomorrow morning (I thought!).  Next morning?  The "service" light was back on!!!  And the truck had not even moved from when I started it yesterday morning!!

So the next thing is, I'm lying down on the floor, mucking about with the plug on the back of the shift controller, pushing the multitude of wires around and all of a sudden the thing squeals like the proverbial stuck pig and the panel lights up and starts to work!!  Well, you KNOW what this suggests!!  I took the plug off again, visually inspected it (such as my crappy old eyes would permit) and could see nothing, top or bottom.  Then I (gently) shook, jiggled, twisted, yanked, tugged and fiddled with, every single wire in the plug, and more or less reorganized them as best I could, and reinstalled the plug and tightened the attachment bolt.

When I turned the key on, the shifter control panel lit up just like it was supposed to, and has continued to do so ever since, and it has now been well over a month and a several dozen starts/stops since then.

My final (?) diagnosis is that it was simply a poor connection between one or more of the pins in the back of the controller itself and the plug with its myriad of individual connectors.  Right or wrong will only be determined in the long run. But, just in case something like this happened to plague one you, I thought I'd share this frightfully enjoyable, frustrating experience.

Beware the electrical gremlins!!
Bret

KU9L
08 December 2009
07:21 AM
Bret
I appreciate your methodology of troubleshooting and reminds me of my days as an electronic technician an test engineer.  I know that when you first start out with investigating this type of issue it can be overwhelming at first, later on you can be deep into the wires like old friends.  The nature of these beasts is that you cannot become so good with them unless you have plenty of opportunities to gain such experience the hard way.  Guys like me not owning our HDT's yet really appreciate this forum as we read every post cover to cover in anticipation of what will be for us as well.

We hope you won't have to write chapter 2 or 3 on this issue at least! ;-)
Dave