Please HELP....6.5 non turbo diesel 4L80E in a chevy p30 school bus will not shift into overdrive.

[Husker6.5]

Like I said above. If the ECM is getting a "Cold" reading from the engine temp sensor, as her (better) mechanic says it is, then the ECM won't allow shifts to OD or the TCC to lock up.

The speedo indicating almost twice actual road speed almost has to be a mechanical issue from the original(?) rebuild that was possibly carried over in the second rebuild - such as the wrong or mis-installed reluctor wheel for the speedo, bad sensor, or mis-set/bad VSSB. It appears to be two separate issues with the same transmission.

I know where there's a good Road Ripper 4L80E in Atlantic, IA, if Jody's P-30 based Trek motorhome hasn't already been salvaged out/scrapped/crushed.

 

[THEFERMANATOR]

As far as I know the only reluctor wheel that will fit in a 4l80e is the 40 tooth. When the reluctor is not present they will sometimes read the parking pawl, but that is only 21 teeth. Even with the speedo reading off, that shouldn't effect shifting as the PCM uses the vssb's 40 tooth output signal which is the output speed sensors signal basically relayed through the vssb unchanged. So this leads me to believe there is an electrical interference problem messing with the output speed sensors output to the vssb. The 2 wires from the speed sensor to the vssb must be a twisted pair(some later models had the vss wires run inside of a shielded/grounded cable, but the wires were still twisted inside). If a repair is made to the vss/output speed sensor wires, the wires MUST be twisted after the repair, otherwise you can get problems like this.

And until you get a scan Tool on it to see what the PCM is seeing for speed from the vssb, don't assume what the speedo is showing is correct to what the vssb is outputting. The calibration resistors used in these clusters WILL fail over time, and when they fail the speedo reads faster than what it is told. I redid turbinedoc's cluster for him awhile back for this exact problem.

The VSSB outputs MULTIPLE outputs(several more than a DRAC does). You have 2 wires that read the vehicle/output speed sensor signal, it then has 1 wire to condition that 40 tooth signal and directly relay it to the PCM for shifting, then you have a dedicated 2k pulse per mile signal that goes to the PCM for the speed limiter, a 4k pulse per mile signal that goes to your speedo, radio, and cruise control, a 128k pulse per mile signal to your ABS, and then another 2k pulse per mile signal for earlier cruise control units. You need a signal generator and an oscilloscope to fully diagnose the vssb and associated circuits.

 

[MrMarty51]

WOW, @THEFERMANATOR
I dont know how You can keep all that stored in Your head. That to Me is just absolutely amazing.

 

[Husker6.5]

WOW, @THEFERMANATOR
I dont know how You can keep all that stored in Your head. That to Me is just absolutely amazing.

When you work with something every day, it becomes second nature and you don't even think about it. That's FERM's "secret". Like when the Fukushima reactor disaster occured. Within minutes of the announcement on the news, based on what they said about the wind speed and direction, I was already plotting out the downrange zones of contamination, radioactivity levels and decay rates for Safe Zones in my head. Just a skill I acquired in the Army as the Distinguished Honor Graduate (#1 in my Class) from the Nuclear, Biological, Chemical Defense Officer's Course and serving as an Additional Duty as the NBC Officer in several units at different levels (Company/Troop, Battalion/Squadron, Brigade/Support Group and Division levels) during my career.

 

[MrMarty51]

When you work with something every day, it becomes second nature and you don't even think about it. That's FERM's "secret". Like when the Fukushima reactor disaster occured. Within minutes of the announcement on the news, based on what they said about the wind speed and direction, I was already plotting out the downrange zones of contamination, radioactivity levels and decay rates for Safe Zones in my head. Just a skill I acquired in the Army as the Distinguished Honor Graduate (#1 in my Class) from the Nuclear, Biological, Chemical Defense Officer's Course and serving as an Additional Duty as the NBC Officer in several units at different levels (Company/Troop, Battalion/Squadron, Brigade/Support Group and Division levels) during my career.

What a career. Thats a skill no ody I know has ever aquired.
I always had some kind of a mental block towards math. I guess I did okay doing the simple math then, someone went and threw alphabits into the equation. My head could not make that fit, then the fourth grade teacher tried to pound that into my head, literally. Many times I would go home with my head bleeding where she had been punching on me. From then on, it seemed I could not learn math no matter the consequences.

 

[Husker6.5]

@MrMarty51, what I learned about Biological Warfare applies 100% directly to addressing the COVID-19 Pandemic. I just can NOT believe the number of morons out there who refuse to do even the most simplest of things to stop this, what in essence is a biological attack, such as masking up, personal hygiene, social distancing, getting vaccinated. If this was say, weaponized anthrax, instead of a naturally occurring new viral strain, the death toll in the United States would be in the tens of millions, instead of the preventable and already too high 630,000+ and climbing.

 

[MrMarty51]

@MrMarty51, what I learned about Biological Warfare applies 100% directly to addressing the COVID-19 Pandemic. I just can NOT believe the number of morons out there who refuse to do even the most simplest of things to stop this, what in essence is a biological attack, such as masking up, personal hygiene, social distancing, getting vaccinated. If this was say, weaponized anthrax, instead of a naturally occurring new viral strain, the death toll in the United States would be in the tens of millions, instead of the preventable and already too high 630,000+ and climbing.

Once when I was in Alaska, a rummage sale, Military family. Here is this bibs and coat, charcoal filled in the lining. Guess I should do some study and see how it is used and for against what.
I think the tag said it can be washed but I’d need to dig it out and read that again.
You probably know about such things and the maintenance there of.

 

[Stefdawson]

Our mechanic called. When he hooks it up to his computer it shifts fine. So we have ordered a new computer. It will be here in 5 days . We are hoping that does the trick.

 

[Husker6.5]

Once when I was in Alaska, a rummage sale, Military family. Here is this bibs and coat, charcoal filled in the lining. Guess I should do some study and see how it is used and for against what.
I think the tag said it can be washed but I’d need to dig it out and read that again.
You probably know about such things and the maintenance there of.

That's a MOPP (Mission Oriented Protective Posture) suit! The charcoal impregnated lining neutralizes chemical agents in both liquid and gaseous forms, such as Nerve Agents, Blister Agents or Crowd Suppressant Agents that happen to penetrate the tightly woven, non-reactive, outer shell. While they can be laundered, once washed they lose their chemical protective capacity and are suitable for only training purposes.

ALSO, wash them ONLY by themselves as the activated charcoal in the lining DOES leach out in the wash and stains anything else in the washer and dryer black! They do this for several washings, too! ALSO, when washing them, run 2-3 EMPTY loads in the washer and dryer afterwards to ensure all charcoal powder residue is gone, otherwise you may be surprised by a load of "clean" dark gray underwear or your wife's favorite yellow dress isn't so yellow any more!

What "training" MOPP suits are great for (besides training for operations in an NBC environment) is staying warm in the winter time! Because of the thickness and construction of the fabric layers, they insulate like crazy and it was recommended during training in temps over 60°F to wear only your underwear in them to help prevent heat casualties and to drink plenty of water, too.

 

[MrMarty51]

That's a MOPP (Mission Oriented Protective Posture) suit! The charcoal impregnated lining neutralizes chemical agents in both liquid and gaseous forms, such as Nerve Agents, Blister Agents or Crowd Suppressant Agents that happen to penetrate the tightly woven, non-reactive, outer shell. While they can be laundered, once washed they lose their chemical protective capacity and are suitable for only training purposes.

ALSO, wash them ONLY by themselves as the activated charcoal in the lining DOES leach out in the wash and stains anything else in the washer and dryer black! They do this for several washings, too! ALSO, when washing them, run 2-3 EMPTY loads in the washer and dryer afterwards to ensure all charcoal powder residue is gone, otherwise you may be surprised by a load of "clean" dark gray underwear or your wife's favorite yellow dress isn't so yellow any more!

What "training" MOPP suits are great for (besides training for operations in an NBC environment) is staying warm in the winter time! Because of the thickness and construction of the fabric layers, they insulate like crazy and it was recommended during training in temps over 60°F to wear only your underwear in them to help prevent heat casualties and to drink plenty of water, too.

Wow, thats some good infurmashun. I dont think I will ever wash it. It hangs in a locker in the garage. Waiting for TSHTF situation to try it out. Guess I should rummage for a SCBA to go along with it. Find a good face covering and I could just use my SCUBA mask, tanks, regulator and the buoyancy compensator to pack it all on.

 

[Buscher13]

When we bought the bus it did not shift into overdrive. Speedometer ran high. Of course this was not told to us at purchase. We thought getting transmission rebuilt would solve the problem. It has done nothing. The mechanic who rebuilt the transmission says I do not know what else to do. We currently took it to another mechanic who is going over everything and definitely is more knowledgable. He called and stated the temperature sensor circuit was stuck "open". So he was going to start with that. Any help you can give me is appreciated. This bus is our home so I need this thing to run. We have not been able to take it anywhere as it cannot be run like this. Thank you all for your help!

Hello all, 2001 Workhorse P42 step van: I have this same issue with Speedo running fast and not shifting into 4th gear. Trans has been rebuilt but still has the same problem. My mechanic thinks it’s the EMC/TCM since it doesn’t look like it is the one that came stock in the van (it has paint marker info on it from a junk yard). I contacted workhorse parts and they said I need this part number #09357159 that they are out of stock. The current ECM in the van has this number on it 16196930 and I can’t figure out what vehicle it came from? Any ideas where I can get a new ECM/TCM or get the existing reprogrammed?

 

[Glagulator]

If you have a vin "Y" L57 diesel engine and 4L80e transmission
then the correct TCM is GM 16196390. Maybe you made a typo?
09357159 is workhorses part num for the same TCM.
Does your TCM have a 4 letter code, like BJDM ?
Could be a bad or wrong VSSB. What is the part num on the VSSB?