New to 6.5, getting DTCs 83, 38, 44, 87

[sathackr]

I'm new to 6.5s and this forum. I've searched and gotten some information on these codes, but not enough to correlate them for a diagnosis. I couldn't find any info on the DTC 38 except for some references to the brake pedal switch. I'm pretty familiar with gasoline engines and have read a good bit about diesel engines and have a general concept of automatic transmissions but have no clue what a TCC Brake would be other than to infer it might be something to stop the torque converter?

DTC 44 - EGR Pulse Width Output Failure
DTC 83 - Torque Converter Clutch Solenoid Failure
DTC 38 - TCC Brake Stuck "OFF"
DTC 87 - High Ratio

I just purchased this vehicle yesterday. I will give as much history as I know.

It's a 1995 Suburban C1500. Odometer reads 395,000 miles. According to the Seller, the engine and transmission were rebuilt/replaced appx. 4,000 miles ago. The batteries were dead when I bought it, so no history codes were present. I personally know the original owner of the vehicle who said the vehicle was meticulously maintained while he owned it. The original owner spent about 8000 on the engine and transmission and put most of the 395,000 miles on it driving between South Carolina and Florida, hauling a 7,000lb loader. I assume this is the rebuild the seller was referring to. The original owner sold the vehicle "because they could never get it quite right after the rebuild". It's been through at least two other owners before I purchased it. The engine appears to have the original block but new heads and a new turbo.

The vehicle starts and runs OK. While idling last night from a somewhat cold start(vehicle had been off for about 2 hours), it threw the DTC 44. I started it this morning, waited for the temperature needle to creep off 160(lowest on scale) and then drove it to work this morning, which consisted of about 15 minutes of 20-45mph driving and about 10 minutes of 65-70mph driving. About 15minutes into the drive, the SES light came on. I immediately connected a code scanner and received the codes above.

The only oddity I've noticed while driving is, when on cruise control, if I tap the brake to disengage it, sometimes I get a decent "thunk" sound, but not every time. I haven't paid close attention to the number/rpms of shifting, but I did notice at 70mph this morning, the engine was turning around 2200rpm.

From what I read, this vehicle should have a 3.42 rear end. The tires are 8 lug.

I just typed this long message and forgot to setup my signature. I will set it up after sending this.

Thanks!
Daniel

[sathackr]

I drove it more today. I am getting gears 1-4 and the tc seems to lock around 55mph. I romped on it once from a dead stop and then backed off at around 65mph. The instant I let off the pedal, before the engine had a chance to wind down, the TC locked with a good thunk and I saw the engine drop from about 2600rpm to about 2000rpm. I figure that can't be good for it.

It almost always throws the EGR code immediately on startup, but that's a bogus code since I have an "F" engine, right (only 1 solenoid on the LR valve cover)? Would that indicate possibly the ECU was replaced with one from an EGR engine?

It also almost continuously throws the High Ratio code and the TCC Solenoid Failure code.

One more thing its doing, sometimes at high RPM (2200+) it starts "Breaking up" is how I would describe it if it were a gasoline engine...seems like it's missing, losing power. I am going to change the fuel filters tonight and do an oil change on it, no telling when the last time any of that was done.


Any ideas on the codes?

[sathackr]

oooook.

After reading a bit I realised there is no code 83 or 87 and thus discovered the language barrier between my code scanner and my truck. I used the paperclip method and got these codes:

DTC 29 - Glow Plug Relay Fault
DTC 35 - Injection Pulse Width Error (Time Short)
DTC 36 - Injection Pulse Width Error (Time Long)
DTC 74 - Transmission Input Speed (TIS) Sensor Circuit
DTC 78 - Turbo Wastegate Solenoid Fault

There is a switch installed on the dash that manually turns on the glowplugs. Any guesses on whether this is the cause, or the symptop of the DTC 29? Maybe the switch was installed because the relay doesn't work. Maybe the Code is thrown because of the switch?

DTC 35/36 I need to search a little on before I ask questions

The DTC 74 would explain the rough locking and unlocking of the torque converter, I believe. Can anyone second that?

I may have caused the DTC 78, I unplugged the connector from the solenoid and started it once or twice, trying to figure out what it was.

I will clear the codes(after I figure out how), do some searching, then hopefully come back with some intelligent questions.

Sorry to waste everyone's time with the bogus codes.

Thanks again :)
Daniel

[sathackr]

I cleared the codes before I drove home yesterday and almost immediately a

DTC 35 - Injection Pulse Width Error (Response Time Short)
DTC 74 - Transmission Input Speed (TIS) Sensor Circuit

were set.

I changed the oil last night and noticed a 2-wire connector disconnected from the transmission, above where the other 2 connectors are.

I re-connected it and cleared the codes again. I drove it this morning and gave it a couple of WOT accelerations, to which it spit and sputtered and fell on it's face. I didn't notice the SES light while I did this, but after stopping I read the codes again. It appears the DTC 74 cleared with me connecting the plug on the transmission, but now the CC doesn't work. The two codes that are set now are

DTC 35 - Injection Pulse Width Error (Response Time Short)
DTC 78 - Turbo Wastegate Solenoid Fault

From reading up on the forums, I take the DTC 35 to mean something's not right with the IP or PMD, correct?. I will check all grounds and connections today.

How can I test the wastegate Solenoid?

Thanks,
Daniel

[Robyn]

Hi

The wastegate solenoid fault is likely due to a failed solenoid.

These are notorious for failures

The Pulse width error DTC 35 is realted to the injection pump.
The ECM expects to get a response from the fuel solenoid in the IP within a specified time frame, when it does not it sets the code.

You might have an issue with the PMD, but generally the issue is with the IP

Yessss, do check all the grounds and make sure to unplug and spray the to main engine harness connctors with contact cleaner and reconnect.

Battery grounds, engine to body grounds and to the frame.
Also there are a few wires at the RH rear of the intake manifold that come from the main harness and fasten to a bolt.

Make sure these are in good order.

Be sure that the ground wire from the PMD harness is fastened to the IP
If your rig has a remote mounted PMD, some times folks will fasten the ground elsewhere.
Ground goes to the IP from the PMD harness, always.

Your on the right track.
Keep us in the loop

Missy

[racer55]

Also codes 35,36 while often can be thrown by a bad PMD-they can also often be resolved by adding a good fuel conditioner with a lubricity additive.

Many people add marine 0 ash 2 cycle oil to the fuel to lube the IP at a ratio of 200:1.

These trucks were not built to run on ULSD and as a result the fuel solenoid can be affected buy it from lack of lubrication.

[sathackr]

Wanted to update the thread on what I've done so far.

I replaced both batteries and the starter. I added a quart of 2-cycle oil to the fuel as well.

I replaced the fuel filter, and while priming the system with the new filter, I discovered the lift pump was not being turned on automatically. The relay and pump are both good. I checked with a volt meter and no voltage is being supplied to the coil. I checked during crank and engine running. I'm trying to locate a diagram of the OPS/Lift pump system to locate the OPS and wires so I can see what's not working. In the mean time I've ran a wire and a switch to manually turn the lift pump on and off.

Surprisingly the old filter wasn't that dirty and the filter manager housing was rather clean of gunk.

I'm still seeing consistently a DTC 35 and 78, and occasionally a DTC 36. I have not replaced the wastegate solenoid yet but can confirm it is not working - I have 25" of vacuum at the solenoid but no vacuum at the wastegate actuator. Not sure if the solenoid is bad or the wiring. I have not checked for duty cycle or voltage at the connector but have tested the coil and get appx 48ohms of resistance. It would appear at least the coil of the solenoid is good.

I noticed a lot of black smoke at any more than about 50% throttle and suspected the turbo was not building boost. I added a boost guage and confirmed this. I tried driving the truck with the wastegate both closed and opened. Either way it only built about 2lbs of boost. Not sure what's going on here but from what I read I should start with checking the crossover pipe and exhaust system in front of the turbo for leaks. The turbo does spin(verified by running engine briefly with the air cleaner off).

I'm seeing what I believe are other symptoms of PMD failture -- a few times, both driving and idling, the truck just abruptly dies. It doesn't spit or sputter, just acts like I turned off the key. Each time it will start right back up without any trouble. It's done this maybe 5 times in 250 miles and 1 week of driving.

It will also often die immediately starting when cold. (Cold is relative...I'm in Central FL) I crank the engine, it fires, runs for 1-2 seconds, then dies again. It doesn't seem to do this when I used the glow-plug override switch previously installed in the dash but I can't confirm the switch prevents it.

I'm building an ALDL interface to use GMTDScan with for more information but will post a different thread on it.

[racer55]

Sometimes the check ball inside the wastegate solenoid can freeze in place,a shot of wd40 is enough to remedy that problem if you are lucky.

You might also want to consider a collapsed crossover pipe since it is double wall construction,along with that a clogged soot trap will affect turbo performance.

[DmaxMaverick]

In all likelihood, you aren't seeing boost because of the codes present. It's probably in limp mode, which reduces fueling. The pump codes can be caused by a poor fuel supply, such as a lift pump not pumping. If it is in limp mode, the cruise (among other things) won't work, either.

Also, have a closer look at the ignition switch and that circuit for lift pump problems.

[sathackr]

Thank you for the replies.


Racer55 -- I tried the wd-40 and tapped on it a bit. If I blow it in the hole with the restriction, it comes out the other. If I blow it in the hole without the restriction, it flows out somewhere behind the metal bracket encasing the solenoid.

DmaxMaverick -- I wasn't aware of the limp mode. That explains why the cruise works sometimes and doesn't at other times.

Would I still see black smoke in limp mode with the reduced fueling?

If the ignition switch is involved with the lift pump then the problem may be there as I know it's been tampered with (The vehicle will crank while in gear) I will look into that area.

Can the lift pump be replaced with one of the generic fuel pumps they sell at the local auto parts store? I see ones that claim to pump 7psi. Or should I replace it with an OEM part? How can I test the pump to make sure it is flowing as it should? I get fuel flow if I open the bleeder at the top of the filter, but I'm not sure how much I should be seeing.

[DmaxMaverick]

You shouldn't see black smoke with reduced fuel unless the wastegate isn't closing. Enough fuel to cause black smoke should spool the turbine enough to prevent black smoke (yeah...a paradox). A plugged air filter can cause black smoke, under just about any condition. Remember..... Black smoke is caused by more fuel than can be burned with available O2. If you have black smoke, it's starving for air, one way or another.

If you have fuel flow with the engine running, it isn't the pump. When you open the bleeder or drain, and the engine doesn't stall, it has enough. OEM pressure ranges from 4-10 PSI at idle. I DO NOT recommend using a "generic" pump. They don't work well with these Diesels, although they may be "Diesel rated". More headaches created than relieved with those things.

The fuel lift pump is powered by the ignition "crank" circuit and a relay while starting. It is powered by the OPS once the oil pressure comes up.

If the starter cranks with the key while it is out of P or N, the problem is more likely the NSBU, or it has been bypassed.

[sathackr]

The lift pump doesn't run on its own during crank or engine running. I have a manual on the way with some wiring diagrams for me. Once I get the manual I should be able to work through the electrical problems, I've been working on gassers for 15 years but diesels and forced air are new to me though I'm familiar with the concepts.

Please forgive my ignorance. I searched for a bit but couldn't find any pictures or information -- Where is the soot trap located? I figured it would look much like a catalytic converter and be located near the engine, but didn't see any such device on my truck. All I see besides exhaust pipe is the muffler at the rear. It it located in the y-pipe?

If I understand the wastegate properly, wastegate closed = exhaust flows through the turbo which generates boost. Wastegate open = exhaust bypasses turbo, no boost.

Lever forward (appx 3 o'clock position) is wastegate closed(boost), lever forward(appx 8 o'clock) is wastegate open(no boost).

[DmaxMaverick]

"Soot trap" is an affectionate term for the catalytic converter. If you don't see it in the pipe, it's been "deleted".

The wastegate is pulled closed, and relaxes open. The actuator is vacuum powered, so it can only work one way.

Your WG functional description is correct (except your second "forward" should read "rearward).

[sathackr]

Update --

I pulled the intake plenum and cleaned up the wiring and grounds going to the IP, including the ground from the PDM(still on the IP)

I found a disconnected cable at the rear of the intake, it had 3 wires and looked like it was going to the bottom of the filter manager. I assume this is the water-in-fuel detector. I reconnected it.

When I pulled the intake, the bolts were barely snug and the gasket didn't look like it was in good shape. I replaced it and torqued them to about 25ft-lbs. Not sure what they should be but that felt about right.

I unbolted the exhaust from the y-pipe and left it disconnected. I still have the wastegate wired closed as the solenoid is bad. Driving it this way I was able to build about 14lbs of boost and it stayed around 5psi at 75mph and 2300rpm. That seems in line with what other people are saying.

I'm not sure if it was the exhaust, wiring, intake, or a combination but it's running much better now. I'm still getting DTC 35/36 but I think I'm wasting my time trying to diagnose it until I get a new PMD and remote-mount it.


FWIW I'm truly grateful for the people and wealth of information on this and other forums. I knew from general conversation before I bought it the 6.5L had a bad reputation. The massive amount and availability of information on them and the helpfulness of people who have been there and done that before is the main reason I bought one anyway. It seems as long as the electrical problems with the IP/PMD are worked out and I don't try to run it like a Duramax and expect 500hp from it, it should be a good engine and treat me well.

[sathackr]

Installed the new PMD today, looks like that fixed it. No codes at all now :)