I hate starting a new thread for a topic that has probably been covered a million times but it would take me an hour to find those conversations so here goes:

I drive a 94 Short Bus 7.3IDI. The bus is converted to an RV and I don't tow any excess weight. I travel alone, keeping the bus with a fairly "light" load.

I get pretty good mileage (highs of 22mpg, lows as 17mpg) but have had an ongoing electrical problem since buying the bus which is an intermittent flashing overdrive light. I've spent $1200 trying to fix it and have been forced to just live with it. In the end, my solution is simply disconnecting the battery anytime it starts flashing. Leave it unhooked for 10 mins- resetting the computer -which kills the error and stops the flashing. When the light IS flashing it causes hard shifting but that's about it. I log a lot of miles (for work), mostly on the highway.

I have had countless suggestions concerning when to drive IN and OUT of overdrive and while I'm sure there's no definitive answer I would like to hear your advice...

My uncle says only use overdrive when on the highway. Rural areas turn it off. Others say, leave it on, only turning off when in rough terrain or mountainous hills.

I'm not concerned about the mileage, just about the health and safety of my transmission. I don't mind only using overdrive on the highway but it seems kinda weird that I would have to manually be turning the thing off an on. Will this cause it to overheat?

Any advice?

 

First, the flashing OD light is the transmissions way of telling you there is a problem. Dont ignore it. you need to scan it and get the codes, unhooking the battery resets the codes. F250 will be along and no doubt will probably be able to help on the transmission thing.

As far as driving in OD, a proper set VSS should have it shifting where it should. Id say you can use OD off the highway, but you dont want it kicking into OD at like 1200 RPM

You are correct you shouldnt have to manuallly take out the OD, with the exception of towing / pulling hills IF the transmission is hunting for gears.

 

having spend 1200 trying to fix your transmission, i'm sure they've tried to diagnose it a few times along the way. what trouble is the computer reporting about it?

with everything working as it should, you shouldn't have to shift manually for everyday driving. no automaker would market a vehicle with an automatic tranny that required manual shifting all the time. so shift it when you need to - that includes up long hills when it doesn't like high gear, down steep hills when you want to take the load off the brakes, and thats about it, just be twice as sensitive to those conditions if you ever are towing with it.

 

I am aware that a flashing O/D light is not something I should technically be ignoring. However, because the computer is so limited on the 94 it only sends back vague codes that don't specify the problem. ALL of the codes that have been scanned have been addressed (hence the $1200), so I've replaced the speed sensor, the TPS sensor, the instrument cluster and tried soldering and repairing old wiring.

All of the transmission guys I take it to tell me that it sounds like an electrical problem and even if they replace the transmission (let's pretend I could afford that) they can't guarantee the problem won't come back.

The electrical experts are the ones who did all of the above repairs, and none of them could offer me a guarantee either. It's hard enough to find anyone old enough to even remember how to work on the electronics of a 94 e350. The guys/gals I've found all tell me it's like trying to find a needle in a haystack. The challenge being that it's an intermittent problem.

It doesn't help that I am mechanically challenged. I probably should have been considered this before purchasing a 1994 Diesel bus.

There is a small outside chance that one of the sensors I had replaced was faulty, but that's probably slim.

 

Thanks for the reply. The $1200 I spent was actually on electrical repairs, (see my post above). The transmission experts did tell me that I shouldn't ignore it, but none of them had the time or apparent desire to want to work on this bus which seems to be the reoccurring vibe I get from most mechanics. They see the look of despair in my eyes and the list of money and repairs I've done, and they figure it's a lost cause. "Screw that!" They'd rather work on cheap plastic cars with computers that tell them exactly what the problem is. Can't blame them.

 

I would start then by finding a new or used harness and intsalling it. From there, replace connections. Ensure first that all connections are clean and have plenty of synthetic grease in there. Im just trying to remember what has been said here before. Best advice i have is send F250HDXLT a message with a link to your thread here. He seems to have the most knowledge / patience with those stupid things than anyone else i know of.

 

I think he did already send me some advice, and yes it was what you said, to grease everything up and check connections basically. It's certainly inexpensive, and at the top of my list, but I just haven't found a mechanic yet willing to do it for me. I'll keep searching, thanks!

Ill be driving 1000km tomorrow and i'll try doing it without turing the OD off and see how it turns out.

 

PS I see you recommend Power Servicee products, maybe it wouldn't hurt to add some of their transmission fix, im sure they have a product like that.

 

to OD or not to OD.
say yes to OD.
if your TPS/FIPL is set correctly,then the ecm will know exactly when to lock/unlock the converter and up/downshift.
let an automatic......be an automatic.the reason the lockout is there,is so that you can lock it out in city driving where the trans may start hunting between 3rd and OD (this is not an issue with the diesel grunt.) or so that you can have a bit more engine braking down hills.
your not going to hurt your E40D trans,by just letting be an auto trans.you will however hurt it,by continuing to drive with a flashing od light/firm shifts though.

clemensfield i recall you asking before.as before im going to recommend the same thing;
forget about paying others to trace it out.it's time (well past actually) to get your hands dirty.
however.since that didn't work.forget that too.let's just do it together via baby steps.

1.buy this:

report back once step 1 is completed.
fear not.i assure you,this wont hurt at all.

 

I have one of those. Kept the code reader, got rid of the E4OD. HAAAAAAAA, oh.... sorry.

 

yeah,but you just miss that blinking light.admit it!

 

That's okay, I have plenty of other issues that keep me occupied.

 

Thanks 250HD, and yes I did copy and paste your advice and showed it to a few mechanics but as you can imagine mechanics don't like to take advice from a mechanically challenged musician who shows up with printed out advice from the internet. They all want to play "MacGyver" and figure it out on their own, which isn't helping my situation.

Yesterday I drove 1100KM (approx700miles) in the bus, all highway. I didn't turn off my overdrive even on steep heels and everything went pretty smoothly. However, the highways in Quebec are pretty brutal and half way into the province I pulled over to take a break, and noticed the engine revving really strangely as I pulled off the exit ramp. It was revving up and down as I came to a stop, which scared me a bit so I shut her down for 20 mins and then set sail again. About 40 min later the O/D started flashing and unfortunately I couldn't pull over because I was in insane 4 lane traffic so I kept going and eventually the light went out. I noticed a similar unhealthy revving/transmission thing going on a few hours later and pulled over and did the same thing, let it cool for 20 mins and then kept going. I made it to my destination, so that's good. I did notice though that the math on my MPG was wrong. I previously stated that i was getting 20-22MPG but I realized that I was doing the math wrong, I'm actually only getting about 16MPG, and that's going 90KM/Hour (55miles/h)

I will buy the ford digital reader you suggested and start from there.

 

Whats your van weigh? 16mpg sounds about right. My boss' wife drive the bus for the local rural community and its a 95 PSD powered shortbus with E40D and she claims it gets 14-15, fair bit of stop and go though obviously. What are your rpms going down the road? Wouldnt be surprised to learn that has some pretty low gearing.

The reving up and down tells me its sucking air, or starving for fuel... or the IP is about done.

 

I don't think it's starving for fuel. By sucking air you mean the Radiator not working properly? I just had the radiator replaced 2 weeks ago, so im hoping that's not it. My temp seems to be better overall since switching the rad. What's an IP? It def does have some low gearing. It likes to go to fourth at about 60km in rural and will sometimes stay there as low as 50km.