Ok I finally got another monty, I bought the one adams77 had for sale. anyway

It doesn't go into over-drive. I checked the tranny fluid and there are two sets of notches on the dipstick. One set is like 2 inches below the other set. Is one for cold check and one for running or what? which one is the set i need to go by?

2 when i engage 4wd the little green light that shows the hubs are locked takes a bit to come on, if i push the t-case shifter up between 2wd and 4h it flashes on but when i go into 4h it sometimes stays off. I was wondering if the hubs are not sleeving and locking or if that light even means for sure that the hubs are not engaged. Is the light triggered by the hubs actully locking or what is the switching mech?

thanks

the light is triggered by the front drive shaft turning.even if you hubs are not locked but you are in 4 x4 this light will still be on.it normaly takes driving for a few feet for it to come on becouse it needs to read a few turns of that drive shaft.

You should have 4 notches. Beginning at the end of the dipstick, they represent:

1) COLD, lower limt
2) COLD, upper limit
3) HOT, lower limit
4) HOT, upper limit

The fluid level should be checked with the transmission warm, after running through all gears for a few seconds each, then check in N or P. The level should be between the HOT limits, preferably nearer the upper limit.

The 4WD indicator lights are activated by 2 switches mounted on the passenger side of the t-case rear output shaft tailhousing. The switches are operated by pressure from a ball & spring (spring is behind the exposed plunger inside the switch) working off of detents cut into the t-case shift rails... as the shift rail slides back and forth causing the ball to move in/out of the rail detent, pressure (or lack of it) on the ball, plunger & spring is transferred to the switch causing it to make or break the indicator light connection.

Check the switches for bad electrical connections... the connectors are pull-apart type... clean them and put a little electrical grease on the pins... don't be surprised if the wires break from age... the switches are available from MMC and are easy to replace, but be careful not to lose the ball inside the housing.

The "Hubs Lock" indicator lamp is activated by a pulse generator on the rear of the t-case, at the butt end of the front output shaft (on the shaft end cover). When in 4WD, the front shaft turns (which includes a pulse rotor mounted on the end of the front shaft), sending a signal from the pulse generator to the indicator control unit. The indicator control unit also receives a signal from the vehicle speed sensor. In order to keep the indicator light on while stopped in 4WD, memory is used in the indicator control unit and it doesn't "wake up" until the speed sensor sends a signal for 3mph. At ~3mph in 4WD, the indicator control unit turns on and the memory keeps the light on when the speed sensor stops sending a signal. When the hubs are not engaged above 3mph, no pulse generator signal is received and the indicator control unit turns off and the light goes out. The light has no idea if the hubs are engaged or not - only that it's told to turn on by the indicator control... which in turn only knows it's receiving a signal that the front driveline is engaged. Is that clear as mud? <img src="/forums/images/graemlins/lol.gif" alt="" />

Now - to the troubleshooting: The pulse generator pickup on the rear of the t-case has 2 green wires... follow them to the connector and unplug it. Check resistance across the 2 pins inside the connector... standard value is between 215-275 ohms..... for reference, mine tests 255 ohms. If the value is outside the spec range, replace the pulse generator. If it checks good, but still behaves erratically, remove the pulse generator from the t-case (1 bolt) and clean the tip... it may have metal particles on it which could cause some gremlins. Further checking would require removal of the rotor cover (5 bolts) to see if the rotor bolt is loose.

Good luck,
Frank

Ok. thats what i thought. So this raises other questions.

1) How can you tell if the hubs are actully locking, is there an easy way?

2) My old monty shifted at like 3000-3200 rpm. My new monty doesn't shift until 4k rpm, and so far it hasn't shifted into over drive at all. At 75mph im running 4000-4200 rpm on 33s, and no shift into over drive. Frome cold and hot check there is too much fluid in the tranny. Is late shift and no overdrive something that might be caused by too much fluid? Is there a way to adjust when the tranny shifts? Any clues?

thanks

Hmmm, Bluebelle doesn't want to go into overdrive when it is cold weather outside. I though it was a thermostat problem. Does fine in warm weather.

Never had the light problem until I got the new/old "Blue" 87, but it has locking hubs.

Short of jacking up the truck, I don't know how you would know if the hubs are really locked.

Shift point is adjusted with the throttle cable at the throttle body.

O/D shift is controlled by several things - temp switch on the thermostat housing water box, O/D solenoid on the driver side of the transmission, O/D switch on the gear selector lever and O/D relay on the passenger side kick panel. An adjustment of the throttle cable may allow it to shift into O/D - I don't know.

Frank

The throttle valve cable is adjusted at the throttle body. First, loosen the screws holding the cable bracket to the intake plenum, and get the throttle cable just short of tight (warmed up engine, please, so all the metal expansion is done) by sliding the bracket on the bolts. Think the slack spec is 1mm or less. Then loosen the two lock bolts on the threaded sleeve on the throttle valve (TV) cable. Slip off the oragne cable boot so you can see the cable exit the sleeve. Note the crimped on brass cable stopper just outside the sleeve. Operate the throttle body lever by hand to wide open throttle, and measure the distance from the end of the cable sleeve to the crimped-on stopper. FSM spec for the distance is 1 5/16"-1 3/8". Mine behaved as yours until I got it dead right. Seems to be very sensitive to small outages. The longer the measurement, the harder the pull on the throttle valve, and the later the upshift, the earlier the downshift, and perhaps (more later) the 3-4 shift doesn't happen at all. Mine is at the upper limit, and I'm going shorter to 1 5/16". It tends to not upshift after a hill downshift while in cruise, unless you tap the decel/set button and let the throttle flop toward closed.

The 3-4 upshift is both hydraulic and electric controlled. My 87 a/t kills 4th gear on overheat, controlled by a thermoswitch on the water neck. Later models kill the upshift while the motor is cold for emissions, again, thermoswitch controlled. It will be a single wire switch, I think, and I think in both cases controls a relay ground path for the relay that controls the OD solenoid valve on the tranny. I bet FrankR has the ODSV electrical diagnostic on the tip of his tongue...

Check the electrical function of the shifter switch, too.

You can hear the hubs hook up, and release, too. A little "chunk, chunk" sound. You can get them to lock up by hand by hand-turning the front driveshaft in either direction. Reverse rotation to check release. In my 85 truck, the directions said opposite direction travel after 4wd disengagement should be 12' to unlock the hubs. Later model says 5'. The former is just under 2 wheel rotations, or about 9 driveshaft revolutions. The later is about 2/3 of a wheel rotation, or about 3 dshaft revs (if the diff is a 4.625). Static testing like this will probably only lock one hub unless the front wheels are airborne so the locked hub can turn while the tardy one locks up. They never seem to do it at the same time.

That's right - spec is 1mm (.04")



Sorry, should have posted the solenoid spec - disconnect the solenoid harness at the connector - it's 1-wire - from the connector pin to ground on the solenoid body (or any chassis ground) should be about 13 ohms.

Frank

Ok so if there is a short in the electrical or a bad temp switch it could cause it to disable OD? Im going to try and adjust that cable today and drain a bit of the fluid and see if that helps. I guess the cable makes the most cents since im shifing at like 4000-4200 rpm instead of 3000-3500. Id does seem to down shift way early too.... Does the cable sound like the most likley bet then?

Ok I drained a lil under a pint of tranny fluid, at hot check it still looks a bit high. The cable slider was at max strech, and the adjusting barrel was all the way out too. I dialed the barrel way down and test drove it around my apts and it seemed like it was starting in 2nd instead of first (i forgot my tape measure so I eyed it). I went back and slacked it a bit, and tried again and it seems good, have only tested from 1 to 2 so shrug. I shifted 1 to 2 throttle wide open and it shifted at 4k, under minimum load it shifted at like 2800 rpm. Before i don't think it shifted before 3500rpm. So maybe that helped. I will drive it to work tomorrow and see if to works or not and post up for you guys.