The dreaded stop, check trans light comes on

[ekgflashnet]

During my last trip, I was seeing with increasing frequency an issue with my stop light and check trans light coming on when stopping at a rest stops.  I would normally leave the engine running while taking a brief rest, but when I would pull out to drive once again, both lights would come on when the transmission tried to shift from 1st to 2nd gear.  I found that if I stopped, turned the engine off and restarted the engine, this condition would go away and I could travel without any further issue.  This would not happen all the time, but was increasing in frequency as the days went on.  I found it did not matter if I stopped the engine at the rest stop.  In some instances the situation would repeat itself.  The worst case occurred when I was stopped at a stop light and when I accelerated, the two lights again came on.  However, by accident, I found that if I released the accelerator quickly, the lights turned off and I could resume.

I'm aware that perhaps the transmission power line going directly to the battery could be the culprit, but I earlier in the trip cleaned this and it had no improvement.  So, when I got home, I looked at the transmission faults which you easily access from the shift panel, and it showed several faults.  Most dealing with the output sensor shaft speed and a fault for output speed sensor 1st gear.  According to the trouble shooting guide, I checked the two speed sensors at the front and rear of the transmission.  But, both were in spec.  As I was reading thru the troubleshooting guide, it said to make sure the power wire and ground was properly connected.  I never thought about ground.  While digging around, I found a single blue wire snapped onto a small protrusion on top of one of the hydraulic lines connectors on the transimssion.  I could see that the connection was quite dirty and quite loose.  I  cleaned it up, and re-tightened.  Took the coach on a test drive, and all looked good.  Only time will tell now.

But for those seeing similiar conditions, try looking for a single ground wire connected to the rear of the transmission housing (side closer to front of coach).

 

stevegg 2005 DDIV

[Frank McElroy]

Steve - Good post.  Very informative on how you went about troubleshooting and more than likely how you solved the problem.  I'll check that ground trans connection next time I'm under the coach doing annual maintenance. 

[granvillebarker]

I’ve also been having intermittent issues with mine.   One symptom I have is the internal oil level sensor stops working.   I’m sure it’s a wiring issue as I can go under and      replug the big connector and it works for a bit.   
 

My last attempt, I tried to take the plug apart on the chassis side, ended up pouring  a cup of fine dust out of it, but I never could figure out how it comes apart.    
 

Thanks for this, I’ll go check the ground today.

 

On another note, on a trip to Alaska my engine kept dying the code said the ecm was loosing power.   It turned out to be the big ground wire going to the engine wasn’t making a good connection.   

—

Granville Barker

05 Dynasty

[hanggiloren]

You would be surprised how many issues are the result of bad grounds on Allison transmissions On my old rig I added a second ground. That helped.

Loren