what made you decide to replace the solenoid pack? what resistance values did you come up with per solenoid? and how did the MLPS check out?
i'v no doubt Mark knows his stuff.but according to:

E40D No Upshifts or Harsh Upshifts/4th Gear Starts
Notes
TECHNICAL BULLETIN # 230A
in the PDF (that was posted on the other site) claims a failed MLPS can cause a 4th gear start.
no one knows/remembers it all lol.plus if you notice its a revised version of #230
Mark could possibly still have #230 on file,rather than the revised version.
remember,testing is free.throwing parts at 'er is not.
plus you only learn by correctly diagnosing.part + hope = nothing learned.

sometimes its best to know when your in over your head,and perhaps it's time to pay a shop to properly diagnose your trans for you.

 

I just replaced it to replace it. I never checked the resistance on the other solenoid, but I will Friday just for the heck of it.

My next task is to check out the mlps.

 

could be torque converter is staying locked up but i think it would stall out of that was the case. just a thought

 

Did not see any one ask is your tach working perfectly and do you have a dim od light

 

What does a dim o/d light mean?

 

I had a similar thing happen to me. The MLPS going out tended to make my truck shift into neutral for no reason, not stay in gear, but it's an easy fix so might be worth looking into.
My first thought was the Torque Converter. Mine went out on my '91 and it felt like trying to drive with the parking brake on. However, if I revved it up enough I could drive it (had to get it home), most times it would just want to stall out the engine though. Ended up having the whole transmission rebuilt. I hope you don't have to do the same! Good luck.

 

How can I find out if the torque converter is going out?

 

Is a 4x2 and 4x4 converter the same?

 

if it was the converter locked up,then she'd be stalling out on you.
what happens when you let off the clutch in a manual truck real quick?
the converter is the auto's clutch (though better in that it doesn't "just" connect the trans to the engine.)
it may be time to re-read this thread to find your focal points.
another reason,you know it's not the converter (besides not having an engine stall condition) is because when you manually shift into R/1/2 you have no issues.....well,besides stuck in 2nd or reverse lol.
that pdf clearly shows you how to test the MLPS,and just get it out of the picture,right wrong or indifferent about weather it can in fact cause a 4th gear start condition or not,your out nothing to test it and should take all of 5 minutes.so why your not coming back,and just saying ok i eliminated the mlps for starters as it tests fine,or bad and you replaced it (cus a failed mlps isn't any good once you address the issue anyway) is puzzling to me.i know you have a meter,i watched it flash in the vid to count codes.

 

Ok a question about testing the MLPS. I read through the technical Bulletin and some of it I am not understanding. When I go and check the ground for MLPS ground do I check the wiring harness or the plug going into the cab? Also it says pin number 30 is the power? I got my test light out, tested it on the battery and it tested good but I tested pin number 30 on both the cab and the harness and didnt get any power.



Where this plugs in dont it go into a little computer box and not into the cab? Could this box be bad? What is it?

And finally I wanted to check the voltage like it says in step 2. Where do I check this at? Where the MLPS plugs into the transmission? How in the hell do you reach it?

The truck only has to have the key on correct and not running?

Just to be clear what settings do I need my meter on to test resistance and then for voltage?

 

ahh,you know what. look at that PDF again.it says "vin code F" way up top.perhaps a failed MLPS causing a 4th gear start can only occur in the latter '94+ psd systems anyway.
this is what i get for not listening to Mark lol.

pull all relays in the distribution box and apply bulb grease.do the same thing to that connecter that plugs into the computer your showing there.then make sure the connecter you repaired is smothered with the grease too.
you need to make sure you have power getting to your solenoids,and like Mark said good grounds.

still,it just can't hurt to test it either.
before you start reading ohms.do yourself a favor and disconnect the + power going to the truck,so that you don't mistakenly test a live wire or you could burn out your meter.of course follow the volt test first though.
the connector your supposed to be checking for the MLPS though (first) is @ the MLPS connecter.it's located on the drivers side of the trans WITH the computer you have unplugged,plugged in still.

so for starters (once you greased up all the connections) turn your meter on and select 20 VDC.
pull the connector off the MLPS down on the trans.
follow step 1,2,3.
before testing resistance,id just disconnect the battery to play it safe with the meter,not just the key off (but probably not necessary.i just wouldn't risk it lol.) never touch the probes to a hot wire while ohms is selected.
do you have the manual with that meter? see that black selection? is that a selection for "auto"? find out,or just use the correct selection range per connection to that chart.

note though,
this is all (probably foolish of me now,based on your latest questions.- my bad) that you've already gone through testing for power and grounds @ the solenoid connector.

oops,some missed questions.
the plug you have unhooked;that the brain that reads from all the sensors on the trans,the vss in the rear axle,brake lights,tach etc.etc.and sends the info down to the solenoids to have the trans shift into the correct gear at the correct time,as well as the other clutch dis/engagements.
testing for voltage at the MLPS,i would think just with the key on,but not running yes.don't get run over by unhooking your mlps with the truck running!!! i dunno what gear she'd pick (if any) in such an event (i guess im hoping for your sake........possibly 4th. ) ,so better be safe than sorry lol.

 

HMM. Would the computer being bad cause problems?

Where are all the grounds I need to be looking for?

 

SHE WORKS!!!!

Took apart all transmission connections and cleaned them up with brake cleaner then filled them all with dielectric grease, and did the same to all the relays. Hmm now I get why they say check connections first.


Now to figure out the ignition problem!

 

sweeeeeeeeeeeeeeeet!!
yeah,my last episode (code 62) i greased the relays (all of 'em) while at the same time put more on the solenoid pack plug (which i thought was pretty good) so this is why i suggested to grease them suckers too.can't hurt that's for sure.
so the relays and or computer harness (possible MLPS connection- we wont know for sure now....dang lol.we'll trust Mark on this one until proven otherwise,but im sure he knows the pre '95 system.so id take his word as gold.)
well,now the no start could be the MLPS (you did get the get code if i counted the meter flashes right,but with dirty connections,those don't mean much anymore now anyway lmao) and could explain why she won't start.or you didn't fully insert the connecter all the way?
for starters,try to start it in park,and then try neutral.
did you make it as far as testing the MLPS values yet? odd,she was starting fine before though,so you may not have got it plugged all the way in.
the MLPS = your neutral safety switch.
if the plug or this part is failing,you wiggling it around,may have fixed the 4th gear start issue (if they can cause a 4th gear start that is) temporarily,but also loosened the connections (internal or external) thus raising the resistance values for park and or neutral.
it's kinda adding up here that the MLPS was,and now is causing all your troubles actually,the more i think about this.
it's all screaming poor MLPS,and im almost convinced a failed MLPS can,and did cause your 4th gear start,and is currently now causing the trans computer to not know your in park,and let you start the engine. - this is all just a theory based on the info at hand.i could be wrong on both reasons,but man,id be surprised.but very well could have just been corroded terminals on the EEC rely.no matter though,one issue resolved onto the next.

should you need to replace the MLPS.all you need for upgraded MLPS connection:
http://www.fullsizebronco.com/forum/...d.php?t=191742

and you know what.iv been putting this off myself.not anymore.im gunna just get this upgraded before she fails.

 

I will recheck the connections on the mlps. Its just weird it just started doing it. I have already tried starting it in other gears with no luck. I never adjusted the mlps nor did I check the ohms or voltages. I do remember a few times before Id get the no start with the key and it would take a few trys to start, maybe whatever it is went out completly? Would a blown fuse be the issue? Id think ignition wise it would either be 3 things, the ignition key, ignition switch, or starter solenoid.

It does start right up with the key on then go out and jump it over.

Can I bypass the MLPS to make it start?