overdrive problem

[jordan]

I have a 92' power wagon 250 with the 5.9L 12V intercooled, A/C, power windows, locks, and lots of electrical problems! My biggest problem right now however is that my over drive will disengage at speeds of 75MPH or not engage at all. I noticed that the problem happens when it's moist or wet out although it still occurs when everything is bone dry, also the tachometer will not read true or not give a reading at all while the problem is happening. But if i step on the brakes the tachometer will work but it still wont shift. my battery voltage drops a considerable amount as well sometimes down to 10V, all these problems come and go at the same time. please help!! I bought a book for the truck but it's useless. (no diesel info at all)

[ISX]

I'm going to say it has something to do with something shorting. Not sure if dodge auto's are the same way, but I think the O/D needs sufficient voltage to engage and lock the tc. Without the voltage, you just get the other gears and no tc lockup. Either way, it surely is all stemming from the voltage drop, which that big a voltage drop has to be a load comparable to the grid heaters, so somewhere you have a very large draw, wires should be melted, or grids sticking on, something like that, a huge draw. If it happens a lot, I'm thinking something is just barely touching until you hit a bump and they arc and fry until they eventually melt apart, awaiting the next bump, if it's the girds, then something is energizing them sporadically. I think I am missing something though so someone else will chime in. This may help you figure out some other issues. http://mopar.mopar1973man.com/cummins/1stgen/wiring/wiring.htm

Edited March 19, 2010 by ISX

[jordan]

Thank you so much, that wiring diagram will be a life saver! one thing i noticed as well just today is that behind my glove box there was some sort of computer box looking thing that was not connected (i left it that way, don't want to fry it) I'm hoping someone will be able to tell me what it does. and if i should re connect it. thank you too all the people that make this site happen, it is an amazing resource (as soon as i'm old enough to get a credit card, I'm donating!)

[ISX]

Alright the PCM is next to the drivers side battery so that scratches that out. So I'm not sure what the thing behind the glove compartment is. I'll keep digging around.

[Mopar1973Man]

Thank you so much, that wiring diagram will be a life saver! one thing i noticed as well just today is that behind my glove box there was some sort of computer box looking thing that was not connected (i left it that way, don't want to fry it) I'm hoping someone will be able to tell me what it does. and if i should re connect it. thank you too all the people that make this site happen, it is an amazing resource (as soon as i'm old enough to get a credit card, I'm donating!)

That is the ABS computer and other stuff (water fuel light etc) I know you can disconnect it but the ABS function is completely lost then. so if you hook it up and the ABS light is stuck on the ABS dump valve is on the rear frame near the axle. Taz has also a 92 Dodge with thesame thing...

---------- Post added at 08:50 AM ---------- Previous post was at 08:44 AM ----------

I have a 92' power wagon 250 with the 5.9L 12V intercooled, A/C, power windows, locks, and lots of electrical problems! My biggest problem right now however is that my over drive will disengage at speeds of 75MPH or not engage at all. I noticed that the problem happens when it's moist or wet out although it still occurs when everything is bone dry, also the tachometer will not read true or not give a reading at all while the problem is happening. But if i step on the brakes the tachometer will work but it still wont shift. my battery voltage drops a considerable amount as well sometimes down to 10V, all these problems come and go at the same time. please help!! I bought a book for the truck but it's useless. (no diesel info at all)

Makes me wonder if the crank sensor is your cause... Because if the crank sensor fails the tach will die or report bad information, and since the alternator is based on the crank sensor to activate the alternator field I would start there because if the voltage drops low the computers PCM and ABS will act really strange and weird.

[ISX]

When does it work again? Does it just eventually work again or is there something else you do that makes it all work again? How periodic does this happen?

[jordan]

it works better when it's dry out. If i floor it to about 60MPH+ and let off it will shift but then kick out when i barely step on the throttle again. also my tach will jump all over the place sometimes staying at the 4,000rpm mark. This problem happens everyday and I'm really hoping i can fix it soon. I'm going to take a look under the truck at the transmission harness, and also look at the crank sensor. If anyone has ohm specs, or any info at all, it would of great help to me. Thanks again for all your help guys! hopefully i can fix this

[ISX]

Ok here is the way to test your CPS.Black/blue tracer is the sensor ground wire. It should OHM close to zero to the battery ground.Tan/yellow tracer is the 8 volt power feed to the sensor. The voltage regulators on the PCM's are kind of loose. This voltage can vary around some. Gray/black tracer is the signal wire. If the sensor is on a smooth section of the balancer there should be little if any voltage showing. When the sensor is on one of the air gaps it should show around 5 volts.

[jordan]

I'm new to this truck so i hope this isn't too stupid a question, but is the CPS off of the harmonic balancer? I also found a link off of this site, I hope it can help other people that might have transmission problems. P.S. what type of transmission do have? http://www.dens-site.net/Dodge_CTD/overdrive_lockout.jpg

Edited March 19, 2010 by jordan
forgot link

[ISX]

Well there you go! I have 5spd, Taz (who moparman referred to) also has 5spd. Moparman has 5spd too

[jordan]

Is it passable or even practical to put a 6 speed manual with high/low O.D i would love to have a 12 speed

[ISX]

Anything is possible haha. 5 gears is plenty for a cummins, in fact 1st is unneeded unless you are hauling something. If you haul a lot, then you might enjoy the extra gear of a 6spd, there is a big gap between 3rd and 4th that the 6spd fills. A 12 spd is downright unnecessary

[Mopar1973Man]

Is it passable or even practical to put a 6 speed manual with high/low O.D i would love to have a 12 speed

Anything is possible haha. 5 gears is plenty for a cummins, in fact 1st is unneeded unless you are hauling something. If you haul a lot, then you might enjoy the extra gear of a 6spd, there is a big gap between 3rd and 4th that the 6spd fills. A 12 spd is downright unnecessary

5 Speed final ratio 0.75:1 6 Speed final ratio 0.73:1 So either trans will twist about the same but ISX is right 3rd, 4th and 5th have some good overlap for trailer hauling. But here is the problem... New Venture the produces of our trannies (5 and 6 speeds) went out of business... The 6 speed series was produced very much and when the parts dry up that it there will be no more made for the 6 speed. But as for the 5 speed there was several models made for the Big 3... so as for the 5 speed parts are starting to be produced by aftermarket companies... Here is a article from Quad 4x4 site.

IMPORTANT! Production of the NV5600 transmission is ended as of January 31, 2005. We can sell new transmissions only as long as supplies last. So, if you are thinking of a NV5600 upgrade or replacement, DON'T WAIT!!!! When they are gone they're gone! TOO LATE, THEY ARE GONE!! Dodge is replacing the NV5600 with a Brazilian made, aluminum housing G56 Mercedes 6speed (originally announced as a Getrag). New Venture/MTM lost the contract to supply Daimler-Chrysler with transmissions. New Venture itself is a now dissolved partnership between Daimler-Chrysler (DMC) and GM. The transmission assembly plant in Muncie, Indiana, is once again part of the GM Powertrain Group and is known as Manual Transmissions of Muncie LLC (MTM). The MTM plant has ceased NV4500 transmission production and the NV4500 tooling and inventory has been sold. Our supplies of genuine NV4500 New Venture/MTM parts is getting tight. At this time, we are sold out of NV4500 transmissions for Dodge applications and for learlier model GM trucks. The supply of new NV5600 transmissions is exhausted. The parts situation for NV5600 transmissions is terrible. How Dodge and MTM could let this situation develop is beyond our comprehension. There are reports of 2005 trucks under warranty waiting for over two months for parts or transmissions. There does seem to be some indication this situation will improve during 2007. We really hope someone takes legal action against Daimler-Chrysler and MTM over this situation. To have new, late model North American built trucks with such lousy parts support is a criminal offense.

[jordan]

Thanks for the insight, i will defiantly take those points into consideration when it comes time to do the swap And as far as the 12 speed is concerned i would agree that it's totally useless, but i love shifting gear in standards, (for now) I'll let you guys know what becomes of it, when i get around to changing it! thanks again for all the help guys!

---------- Post added at 07:20 PM ---------- Previous post was at 02:30 PM ----------

So i took a look at the wiring and it's all sh!t, there's only about 1" of uncut wire loom! so i think i need to re-wire the entire truck. who ever had it before me used house wire in some spots! as-well the transmission cable going to the VE pump is loose and sticky (probably not adjusted) I haven't checked the CPS yet (my brother recked my multimeter) Does anyone have a full wiring diagram i will be documenting all my work and posting it for others including wire lengths, colors, and possible improvements to the system.

[Mopar1973Man]

So i took a look at the wiring and it's all sh!t, there's only about 1" of uncut wire loom! so i think i need to re-wire the entire truck. who ever had it before me used house wire in some spots! as-well the transmission cable going to the VE pump is loose and sticky (probably not adjusted) I haven't checked the CPS yet (my brother recked my multimeter) Does anyone have a full wiring diagram i will be documenting all my work and posting it for others including wire lengths, colors, and possible improvements to the system.

Well it looks like you might consider looking in the bone yards for a wreck truck in better condition than your own and swap the electrical completely over... Taz's truck is bad but not that bad... It seems that all the older truck tend to get completely abused and hacked up trying to fix the problems...

[ISX]

Old wiring sucks! But even worse is wiring that is not factory because of previous owners. At least you don't have that many wires I don't think it would be all that hard on my truck, and I can't access them as easily as you can. Just take your time, measure twice cut once..

[jordan]

I may consider the wreckers idea, although i do enjoy doing the work. and I will know all my work is new and done right. as-well the same brother that fried my multimeter, is almost done school for an electrical engineer, hopefully he learned something and can help me. Either way i think there will be a wiring diagram by the end of this for others to use!

[jordan]

So I went for a drive around town today and noticed something very strange about the O.D condition. The tac and volt meter only screw up once the engine reaches temp! untell then they are fine and if i turn the truck off and restart it 10min later it will be ok until it warms up again. it doesn't have to be at full temp for this to happen, only around half of operating temp! any ideas?

[ISX]

I am just trying to figure out why the voltage drops. You should unhook the 2 positive grid heater leads, wrap them in electric tape, and see if that makes any difference. Make sure truck is halfway warm If the alternator stopped working, it would just drop to 12, the grids are the only thing that has a big load like that. A short would do it too but I assume you don't see any melted wires, or leads touching each other. If you can figure out whats pulling all that load, it would probably solve all the problems. Not sure why the engine temp does something but who knows if the wiring is all homemade.

[jordan]

I had the same thought today about the grid heater, I'm going to unhook it tomorrow. I also thought maybe it has something to do with trans temp sensor? maybe it's causing some sort of chain reaction that ends up tuning on the heater grid. I have a digital power inverter with voltage display and it stays at 12.1V when the voltage is down (exactly like when the heaters are on) I will keep you guys updated on the situation. We'll see what tomorrow brings! P.S. lighting, turn signal , and brake wiring is completed on the diagram working on engine and trans part now:thumb1: