AutoShift Problem -- update

rv_safetyman · May 05, 2010, 05:08:41 PM

This is an update to the problems described in this thread: http://www.busconversions.com/bbs/index.php?topic=15496.0

I have received many wonderful emails and phone calls asking how I am doing and how things are going. Well, I have not been sitting around eating bon bons

I have had the luxury of having a bit of time before our next trip, so I have been approaching this issue in a bit of a round about path. So, try to follow along.

Many of you know that I have had a big charge air cooling problem. My original design was to use four high capacity electric fans to force air through the CAC. That did not work well. If I had a big side wind on that side, things were fine, but driving up a big hill caused temperatures well above acceptable. I think the big issue is that the electric fans could not overcome the static pressure caused by pressure under the bus. I have been gathering parts to install a hydraulic fan. I had made a pact with myself that I would not make another trip until I had the hydraulic in place.

How the heck does that fit with the transmission trouble shooting? Well, the transmission would throw a fault code within the first few yards of driving. So I thought that I could do the initial trouble shooting in the shop. I had to get the drive axle up on blocks. I have great hydraulic jacks installed on both the front and rear of the bus and it made sense to use them to lift the bus. Problem was, I have only hooked them up to a remote 120 V power pack and that was really jury rigged. SO (are you still with me?), it just made sense to work on the fabrication of all of the hydraulic system components needed for both the jacks and the fan. That was no small task (I will bore you in a month or two with an article in Bus Conversion Mag.).

OK, today I got the hydraulic system working (new pump works great with the power steering and the fan/jacks). The bus drive axle is up on blocks.

But the real bottom line of this preliminary report is that I was able to replicate the fault code late this afternoon!!!! Now I can pick away at the troubleshooting process.

Stay tuned.

Jim

robertglines1 · May 05, 2010, 05:58:14 PM

on edge of seat!!will definitely file result in future troubleshooting

DMoedave · May 05, 2010, 06:29:28 PM

Hey Jim, can you ever really go out to the bus and end up working on the initial problem without moving,fixing,finding,searching,sidetracking,etc? I will be very interested in how you solve your cooling especially how you pull the air in and send it back out. How the air flow over under and around these buses and how the coolest air is sent thru the cooler and radiator is somthing i have been wondering about. Good luck on your trouble shooting and thanks for keeping us updated.

TomC · May 06, 2010, 09:11:21 AM

Jim-I know when I installed my auxiliary trans cooler with electric fan, I first tried to suck in air from the outside, which didn't work since the little electric fan was trying to work against the big radiator fan. Then I changed the direct to pushing air from the engine compartment outside, and it works well. I know that the engine compartment is hot, but it is still cooler then the radiator coolant. Just a thought if you might want to try that also. Good Luck, TomC

rv_safetyman · May 06, 2010, 10:59:19 AM

Hi Tom.

I went through all of that - blowing in and out. Finally built an enclosure so that the engine fan would not impact the flow. With that setup, I have the fans pulling outside air in and exhaust out the bottom of the bus.

I think that there is some pressure under the bus. Partly from the engine fan, but also because of air flowing under the bus when your are going down the highway. I have the material to put a dam right behind the axle, but have never gotten around to that project.

I think that the electric fans are just not good if there is any pressure on the downwind side. They work fine on the front of a car, since the natural air flow helps them.

Jim

bevans6 · May 06, 2010, 11:13:55 AM

It's generally felt that fans on the front of a vehicle only are useful under a certain speed, usually around 30 mph. Over that natural airflow is far stronger than the fans could ever be. I think, based on some work I've done, that the air pressure under the bus should be a fair bit lower than at the rear side of the bus, and that the air pressure behind the bus will be lower still, but quite chaotic. If under the bus isn't working, you might try flowing from the side of the bus to the rear of the bus.

On my race cars we often pull air in from the sides and exhaust into the engine compartment, which is open to the rear or to the sides and is quite low pressure. We never run fans at all.

Brian

rv_safetyman · May 06, 2010, 03:47:56 PM

OK folks, here is where we are at.

First I will discuss the original transmission ECM (the one that put us on the side of the road). I had done quite a bit of trouble shooting on it when we were parked and it looked like it was toast. It would throw a code a code SID 40 which is a gear selector motor fault. However, it had some other symptoms that were strange. When I followed the trouble shooting to the end, it said that the ECM had failed.

Next, I put an ECM in from a transmission I had in the shop (had to make a trip home to get it

). That was the one that would only go a few feet in the starting gear (2nd) and then throw a code PID 161 (input speed sensor). When we were on the side of the road, I contacted our local Roadranger technical person. We did a lot of trouble shooting and neither one of us could figure out what was going on. In spite of the input speed sensor code, I could watch the input shaft speed on my Pro-Link and it was reading correctly (consistent with engine RPM). That was when we gave up and called THE HOOK

Today, I started trouble shooting the ECM that was throwing the PID 161. It did throw the same code every time I engaged the clutch and reved the engine a bit to simulate taking off. I replaced the input speed sensor with a spare I had and got the same result.

Then I put in an ECM that I had borrowed from a friend. That ECM seems to work just fine. I got it to shift a gear (not easy when the wheels don't feel the inertia of the bus), but it seems to work just fine.

Just to be sure, I put the original ECM and it again showed the same failure traits.

So, tomorrow I will get the bus off the jacks and take it for a drive with the borrowed ECM. At least I hope I will, since there may be some snow at our elevation. I expect it to work fine.

I will contact the Roadranger person and see if he will reprogram the ECM to see if it is a software glitch. The person I got the transmission from was having some problems, but I think it was related to a harness problem. He did not describe a problem like the one I am having.

Tom C, if you are out there, would you mind seeing what the transmission ECM (generation 1) goes for? I am afraid to ask

Jim

rv_safetyman · May 06, 2010, 05:53:26 PM

Project will be on hold for a few days.

We just learned that a very special relative just died after surgery. 54 years old and one of the best people I have ever known.

We will be heading out to Iowa in the car tomorrow or Sat.

Jim

John316 · May 06, 2010, 05:59:03 PM

Jim,

That is very sad to hear. I am sorry. We will keep all of the family in our prayers during this tough time.

God bless,

John

JackConrad · May 07, 2010, 05:24:49 AM

Jim,
Our condolences to you and your family. Give Pat a big hug from us. We will keep ya'll in our prayers. Have a safe rip, Jack

rv_safetyman · May 13, 2010, 08:40:03 AM

We are back home. Welcomed by snow!!! We have over 4 inches on the deck – it is May for crying out loud!!!

Thanks so much for the kind words here, via personal email, phone calls, cards, etc. It was a very tough trip. A real roller coaster of emotions.

Now, back to the AutoShift problem. Off-line I wrote to TomC to see if he could find out how much the ECU replacement would be (well over $2K

). In preparation for that request, I went to my parts manual (electronic version on my computer). It showed three different part numbers - one each for the different gear ratio sets in the transmission.

Monday night as my tired head hit the pillow, the light went on!!! I am pretty sure that my replacement ECU is for a different gear set than my transmission. That would explain the fault code in the first few feet of travel. The ECU expects to see a specific shaft speed relationship for each gear. When it does not see that relationship, it throws a code (in this case it says I have a bad input speed sensor – I know that is not the case). To confirm this theory, I called the local Roadranger rep. (a very helpful person) and he confirmed that my theory is probably correct.

He can reprogram my replacement ECU for the correct gear set and I should be good to go. His schedule is such that we can't do the reprogram before we have to leave on our next trip. I will use the loaner ECU (THANKS Wayne) for the start of this next trip and have the Roadranger guy ship my unit to me when I am on the road.

If you have followed all of my "tribulations", you will note that switching computers has now bitten my twice. Hopefully we are "on the road to recovery".

BTW, I have talked to Sonnie Gray several time and profusely apologized to him for all my negative comments about mechanical engines and begged him to remove the hex he has placed on my bus

.

Jim

rv_safetyman · May 13, 2010, 03:12:21 PM

I did check the transmissions involved. My transmission has the "C" gear set, while the donor has the "B" gear set. That pretty much confirms the theory of why I got the error code on the replacement ECM.

Funny, I carry lots of spare parts with me, but there is no guarantee that the part will work.

Jim

robertglines1 · May 13, 2010, 03:50:43 PM

Jim I wanted to thank you for following up with your findings...and hopeful solution ...fingers crossed...I'm just starting out on the autoshift adventure and need to file all the info I can about problems that might arise....Bob

DMoedave · May 13, 2010, 08:44:28 PM

That is just great! Love those lights going on and hope it pans out. My thanks too for your posts and followups. And for the repower articles.

NEO/Russ · May 14, 2010, 07:07:07 AM

Jim, I have a Gen I, "C" ratio A/S in my Kenworth. I have a spare ECU that I got from eBay, but after reading your post I wonder if I have the correct one. Do you mind sharing the part numbers. The Eaton information available on line is awesome for support, but in all mine I couldn't find a page with part numbers. The operators manual, installation manual, service manual, troubleshooting manual, yes, but no part listing.

Thanks, Russ