6.5TD no fourth gear

[Rally91]

Ok I have looked far and wide on the internet..... At a fresh start-up the truck will not shift into fourth, BUT after driving around a while the Service Engine Soon light comes on then fourth and OD starts working. This continues until the truck is turned off and when restarted (even seconds later) the cycle starts over. This has just arisen suddenly and the code came up as a brake light switch, which has been changed with a new one. Any ideas? thanks in advance!

 

[bison]

Have a hard look at the new brake switch,...it could be a dud out of the box.
And check the Br Switch connector and wiring,....don't forget the grounds.

 

[Mudbath]

Ok I have looked far and wide on the internet..... At a fresh start-up the truck will not shift into fourth, BUT after driving around a while the Service Engine Soon light comes on then fourth and OD starts working. This continues until the truck is turned off and when restarted (even seconds later) the cycle starts over. This has just arisen suddenly and the code came up as a brake light switch, which has been changed with a new one. Any ideas? thanks in advance!

Was the brake light switch changed and then this started or have you changed it to try to fix it? What is the code?

 

[Rally91]

The code came up first as the brake switch and was changed with a new one. There was no change in the truck after the switch was changed and I haven't yet went to see what the code is.

 

[635]

Lost my overdrive years ago. Went to the stealership, long before these sites were around. Code said brake light switch. They cleared the code, for $86.00, I left went to the parts counter and bought one and installed it, left and same problem came back, no overdrive.
Went to a transmission shop the next day and they found a code and it said pulse width modulator, transmission shop installed it and everything was fine.

 

[Brooklyn Tow]

Lost my overdrive years ago. Went to the stealership, long before these sites were around. Code said brake light switch. They cleared the code, for $86.00, I left went to the parts counter and bought one and installed it, left and same problem came back, no overdrive.
Went to a transmission shop the next day and they found a code and it said pulse width modulator, transmission shop installed it and everything was fine.

Experience proves to be the best tool........Very often.

 

[gmctrucksrock]

not saying this is it but if coolant temperature sensor is unpluged which i do to cold start sometimes overdrive will not engage

 

[Rally91]

Ok I was able to take the truck and get codes tonight,
there were 4 codes one twice....
DTC 24
DTC 24
DTC 22
DTC 49

From what I can see so far is that it needs a speed sensor, throttle position sensor, and the light for "Service Throttle Soon" is out. Am I correct?
BTW that was the exact code order

 

[WarWagon]

You need a throttle pedal assy not a TPS. First check wiring and grounds. The output speed sensor connector wires are known by me to have the insulation flake off and short out. Check this first. Then clean the grounds by the trans oil dipstick rear of engine.

Computers this old flake out reading out codes and sometimes double the first one. Again check voltage both grounds and positive including battery cables and load test the batteries.

Check the throttle bulb and wires. also check and clean fuses...

 

[great white]

I hope it's not your app ( throttle pedal).

Those suckers are expensive....

 

[Rally91]

Ok it looks like it was the wires near the transmission, they were crispy and some were broken completely. Now the truck has a stutter in 2nd gear at about 2000RPM until the truck gets warm all the way, then rarely stutters.. Is this a problem with the MAP sensor?

 

[great white]

Repair wires, clear fault codes, drive truck, pull new fault codes.

That's a start now that you've made a repair.


Sent from my iPhone using Tapatalk

 

[WarWagon]

Ok it looks like it was the wires near the transmission, they were crispy and some were broken completely. Now the truck has a stutter in 2nd gear at about 2000RPM until the truck gets warm all the way, then rarely stutters.. Is this a problem with the MAP sensor?

You can throw parts at a 6.5 all day long and get nowhere. You really have to troubleshoot things and hunt the problem down. Start with cheap simple things like trans fluid level and condition. Grounds are famous for causing trouble as well as positive battery cables corroding. What is the lift pump pressure? Does the lift pump quit with the engine running from a bad Oil Pressure Switch, aka OPS? Any codes in the computer after clearing them with the last repair?

As 2000 RPM is around peak torque: Check the drive line, U-Joints, carrier bearing, engine mounts. 4WD locked in or front diff locked in from bad motor?

Check the fuel system. Age of PMD? What did the fuel filter look like? Screen in Fuel filter housing? Have you put a clear return line on the IP and checked for air? Hiss from gas cap opening tank?

 

[THEFERMANATOR]

And you should fill out your sig so we know what you have. If this is a 91-93 it is a pretty differrent process of diagnostics than the 94+ with electronic pump. This could be an engine problem, wiring issue, or an internal trans issue. First let us know exactly what you have, then tell us when it started, and what has been done to it in order and if anything changed with each thing you did to it. Throwing parts at a problem wil lalmost always cost you more money in the end than diagnosing and repairing the actual problem.

 

[Brooklyn Tow]

And you should fill out your sig so we know what you have. If this is a 91-93 it is a pretty differrent process of diagnostics than the 94+ with electronic pump. This could be an engine problem, wiring issue, or an internal trans issue. First let us know exactly what you have, then tell us when it started, and what has been done to it in order and if anything changed with each thing you did to it. Throwing parts at a problem wil lalmost always cost you more money in the end than diagnosing and repairing the actual problem.

FERM is right......we need more info!


http://www.thetruckstop.us/forum/showthread.php?6300-6-5-Engine-Diagnostic-Troubleshooting-Checklist

 

[Rally91]

Problem: Explain your problem in concise language (ie: Cranks but won’t fire). Truck stalls (does not die) when in second gear at around 2000 rpm doesnt improve until it makes it to third gear, then stops completely except for a few rare fishbites. This happens when the truck is cold and when the truck warms up to around 180 the stalling stops and is limited to fishbites that are random.

Demographics: tell us about your truck and your ambient conditions:

- Year: 1995
- Truck model and class (ie: c2500) K3500
- Automatic or Standard Auto
- Mileage: (indicate miles or km) 195000
- Replaced parts and mods (IP, PMD, chip/PCM, TM, injectors etc) Complete front end rebuild, glow plugs, injectors, fuel pump, PMD relocated (done by PO unknown when done)
- Model: ‘S’ or ‘F’ engine, NA or Turbo, EGR?
- Ambient outside temp: (indicate *C or *F) 60 f
- What fuel are you using? (#1 Diesel, #2 Diesel, Bio, VO, WVO, etc) _________
- What fuel additives are you using? ___________
- Where are you located? midwest

General maintenance: inspect and evaluate the condition of each. When were they last changed?
- Air filter just replaced
- Fuel filter just replaced
- CDR Valve? _________
- Coolant – last flushed/replaced at just replaced
- Oil – synthetic/regular, changed at _just replaced__________
- Batteries – state of charge, (matched set) replaced at _very recent____________
- Battery cables and grounds (removed, cleaned and tightened): ____yes__________
- Glow Plugs - how many miles on them? ____100_____ What type? _____________
- Injectors - last changed at ______just replaced_________


History: (Describe how the problem first appeared.)
- What were you doing when it happened? _____coming from dead stop at sign_________
- How was the truck running fine before this problem appeared? _____yes started as small fishbitting________
- Has this problem ever happened before? __________rarely_____________
- Describe any related factors that might be part of the problem. _____bad transmission wiring (fixed)_________
- Have you checked for DTC (Diagnostic Trouble Codes)? (Y.N) __y__ And? ___none_____


Diagnostics:

1] Starting:
1a] Does the engine start? _________y
1b] Does the engine crank over? _____y___
1c] Are your batteries fully charged? __y_______
1d] Have you removed, cleaned, and tightened all battery connections? _y_______
1e] Does your Wait to Start light come on for a time? How long? _________
1f] Does your glow plug light come on? ___y______ For how long? ___2 min maybe______
1g] Do you see smoke from the exhaust while cranking? What color? ___n_____
1h] Does the Service Engine Light Glow during Start/bulb check? ____y____

2] Fuel Issues (if not running):
2a] Can you hear your lift pump working? ____________
2b] Do you get a steady flow of fuel from the water drain (T-handle) ? _________
2c] Loosen the inlet line from the IP – is fuel coming out (Lift Pump on)? ___________
2d] Loosen an injector line and crank the engine - does fuel come out? _________
2e] Do you hear a vacuum (hiss) when you remove the fuel cap? ___________

3] PMD / IP Issues
3a] Location of PMD (on pump, on intake, remote mounted) ____remote in front of radiator_______
3b] Condition of Extension harness (if used) Vendor or Homemade? _____vendor____
3c] Condition of grounds / ground wires to IP / PMD. Check Harness. ___good______
3d] PMD Make: ___________
3e] PMD Age: _____________unknown

4] Stalling Issues
4a] Do you experience stalling only when hot? ______n______
4b] Does it stall under particular circumstances? (ie hit bump, or on accel) __accel 2nd gear____
4c] Does pouring cool water over the IP seem to help with restarting? _________
4d] Is stalling momentary (engine recovers)? _________yes
4e] Does SES light come on when engine hiccups? _______no__
4f] Does cruise control quit working when engine hiccups? __unknown_________
4g] Does re-starting seem to reset engine, restoring cruise and power? ___n/a______
4h] Changes to dash lights or instruments during stalling events? ____no_______

5] Running Issues
5a] On cold start, does upper rad hose get hard before engine warms up? _______
5b] Any bubbles or oil film in coolant overflow tank? _______n
5c] Any white slime on oil surfaces (dipstick, CDR, oil Fill cap)? ____n______
5d] Excessive white smoke from exhaust on cold start? _____n____
5e] Excessive black smoke from exhaust under hard acceleration? _____n_____

6] Performance Issues
6a] Do you have gauges (boost, EGT) ? ___________n
6b] Maximum boost under load? ____________
6c] Have you added a performance PCM (reflash) or Chip? _______n_______
6d] Have you changed exhaust / downpipe / crossover? __________new oem______
6e] Wastegate – mechanical or vacuum (OEM)? ______________

7] Temperature-related Issues:
7a] Single or dual thermostats? ____________
7b] Have you replaced them lately? Manufacturer of replacements? ________n_
7c] Have you pulled and cleaned Radiator and coolers lately? ____________n
7d] Have you replaced the fan clutch? Manufacturer of replacement? ______n__
7e] (winter) Have you tested your antifreeze? Good to what temp? __________
7f] (winter) Are you using a winter grille cover? ___________n

List and describe any other factors which are not addressed in this checklist. We can’t see, hear, smell, or touch your truck, so the more descriptive information you can give, the more likely it is that somebody can assist you.

_________________________________

 

[Rally91]

Here you go guys I hope this helps you help me. BTW wiring has been replaced and this stall issue started to show up BEFORE the loss of fourth gear. Truck shifts like it did before the problems occurred. Havent had this truck too long, just a few months, and the PO did not give too many specifics on replacement parts.

 

[WarWagon]

By the description you need to check out the fuel system. Sounds like it is starving for fuel from a bad lift pump or plugged tank sock. Possible it is even sucking air from a leaking fuel pickup and/or fuel filter manager with bad lift pump.

Is the PMD on the intake or in the bumper? Does the cruise control work?

Any codes in the computer?

You can remove/bypass the optical filter harness and see if that helps.

The list is useful as well as your signature. Having to guess what you have by trouble codes can be done...

 

[Rally91]

Im not getting any codes now since we fixed the transmission wires. We had also found that the MAP senors were disconnected and the cut out has gotten better, it doesnt always do it when cold and it seems to do it only when under load ie hills/passing after the truck warms up a bit.
We are relatively new to diesels and will definitely need help locating some of these things you have mentioned.
Also the MAP sensor on the firewall (driver side) has a vacuum nipple with no vacuum line attached, is this normal?

 

[WarWagon]

The MAP sensor on the firewall is a Barometer sensor as you can't use a MAP on the manifold to read baro on a turbocharged engine. Normal for it to not be connected.

Start here and check out the technical reference library section...
http://www.thetruckstop.us/forum/sh...t-Pumps-amp-OPS-operation-and-troubleshooting