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Winnebago on a p30 chassis with a 6.5l diesel and 4L80E transmission stuck in limp mode?

benh84

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Morning all.

I recently bought an imported Winnebago RV in the UK. It's a 97 model on a 1996 P30 chassis. There are so few here and knowledge is very limited, my plan is to get it back working and on the road, before moving in with the family and travelling full time around Europe.

I've got a problem with the vehicle, which I think is transmission related. I'll explain what I've done so far.

I've got an OBD2 port, with only 5 pins (1 at pin 16 so I have a powered port.) I can read fault codes with an OB2 reader, but I believe it may be an OBD1 system, as info is limited. I only had 1 inactive fault P1218, which is something to do with the fuel injection system. I cleared it, MIL light cleared and fault did not return. I don't think it was related to the issues I'm having.

The vehicle has sat unused for 7 years and has 41,000 miles on the clock. Before doing anything I changed the engine oil/filter and fuel filter.

The dipstick for the transmission was broken, and I made a new handle to remove and check it easily. I dropped the pan and reset the level of the dipstick to be where the pan meets the transmission housing, as advised elsewhere. I then topped up the transmission with new fluid. It took about 1.5l more than removed. The old oil was dark in color, but did not smell burnt.

When selecting gear, it is sluggish to pull away, but picks up speed quite nicely once moving past 5mph. It does not change up or down gear at all. Reverse works. This leads me to believe the vehicle is in 2nd gear and issue is to do with the electrical system, causing this limp mode as such.

I checked the transmission fuse (10a) and there is 12v at the gearbox connector.

At the connector, I checked the resistance of:
1) Solenoid A - was good.
2) Solenoid B - was good.
3) TCC - was good.
4) Force motor - was good.
5) Transmission fluid temperature switch (TFT) - nothing. (I was expecting between 4 - 6 ohms).

I suppose with no fault codes, this is an electrical issue, causing the transmission not to shift and remain in it's limp mode state. My speedometer works as it should, so does that rule out the input and output speed sensors? Would the TFT, cause the limp mode, or is it even at fault?

I appreciate any guidance on this, as I need to get the vehicle roadworthy as soon as I can. Thanks.
 
Welcome @benh84 as you are able to read codes communicating with the PCM, what scanner are you using to pull codes. you will need to be able to read some live data as you attempt to drive the rig. this will tell us if the PCM is commanding the trans to change gears.
 
I’ll just say welcome- my questions already asked above except post a picture of the turbo (if it has one) as well.

And remembers most of us are Americans that will answer, so where to mount a gun rack is probably gonna come up. Haha
 
Big thanks to everyone for the replies.

Welcome @benh84 as you are able to read codes communicating with the PCM, what scanner are you using to pull codes. you will need to be able to read some live data as you attempt to drive the rig. this will tell us if the PCM is commanding the trans to change gears.
In all fairness, I was using a cheap Bluetooth code reader, but I can plug in with another decent bit of kit at work tomorrow. I did check that both my speed sensors were putting out readings whilst moving.

Take a picture of the injection pump. Also see if you can find the PCM and take a picture of it as well. Pics of top and bottom of PCM.
I'll grab this in the morning when I'm back with the Rv. I'm assuming the large unit under my dash is the ECU, is the PCM likely to be around there? I haven't noticed it anywhere, but I'll take a look.
The cooler lines go to the front of the transmission, its the earlier model and has the filter with no dimples on it.

I'm back with the vehicle in the morning, so will remove the doghouse and grab some photos.

Thanks again.
Ben.
 
what we call a PCM is the same as the ECU. Powertrain control module which is the brain for both the engine and trans. since your's is a 97, it is OBD2. in an RV it can be located anywhere under the dash, under one of the front seats or in a compartment up front somewhere.
 
what we call a PCM is the same as the ECU. Powertrain control module which is the brain for both the engine and trans. since your's is a 97, it is OBD2. in an RV it can be located anywhere under the dash, under one of the front seats or in a compartment up front somewhere.
pcm powertrain control module
Ecm engine control module
For some of these vehicles engine and transmission are controlled by this unit having two different names.

For other 6.5 vehicles it is known as a TCM transmission control module.
These engines have a db2 injection pump (ip). It is controlled by a throttle cable not electronics. No computer is used for the engine.

MOST of the time an obd2 port indicates ds4 electronic injection pump that needs the controller for the engine. NOT ALWAYS. Hummers, many vans, p serious chassis, etc can have a db2 ip with no electronics on the engine and have an obd2 port.

Configurations changed by year in the pickups but not in everything else.
My 1995 Hummer is obd2 with a TCM and db2 for instance.

GM played loose with the obd1 & obd2 ports so never use them as an identifier.
 
what we call a PCM is the same as the ECU. Powertrain control module which is the brain for both the engine and trans. since your's is a 97, it is OBD2. in an RV it can be located anywhere under the dash, under one of the front seats or in a compartment up front somewhere.
I'm used to working on buses, over here there are multiple control modules. Usually because the companies building the vehicles, have a different brand engine, transmission and even exhaust systems, all have their own modules. Real pain when you're trying to solve problems that overlap between systems.

Well, the RVs PCM is what I would have seen behind my dash today, fairly big, has 3 plugs go into the bottom. Top is pretty well buried. I'll grab some photos tomorrow.
 
pcm powertrain control module
Ecm engine control module
For some of these vehicles engine and transmission are controlled by this unit having two different names.

For other 6.5 vehicles it is known as a TCM transmission control module.
These engines have a db2 injection pump (ip). It is controlled by a throttle cable not electronics. No computer is used for the engine.

MOST of the time an obd2 port indicates ds4 electronic injection pump that needs the controller for the engine. NOT ALWAYS. Hummers, many vans, p serious chassis, etc can have a db2 ip with no electronics on the engine and have an obd2 port.

Configurations changed by year in the pickups but not in everything else.
My 1995 Hummer is obd2 with a TCM and db2 for instance.

GM played loose with the obd1 & obd2 ports so never use them as an identifier.
Thanks.

It certainly seems like a bit of a mix. I suppose for the P chassis like mine, it was registered by Winnebago in 1997, but the chassis was built in June 96. Years ago, I had a ford around this age, had a similar problem, where multiple parts were used from new spec and old. Can be a real pain when you're trying to work out how things should work and for buying parts too.

I'll grab the photo of the turbo (as far as I know it does have one, but i can't recall seeing it) and injection pump too, as someone asked for that.
 
Right, I've been to the vehicle this morning. The Jaltest kit at my work doesn't have access to the engine and transmission type for truck, so I can't get decent live data from it.

I'm going to try something else later on.

I managed to get the following photos of the turbo, injection pump and PCM as requested.

1000000936.jpg1000000935.jpg1000000937.jpg1000000938.jpg1000000940.jpg1000000941.jpg
 
OK, you have a DS4 injection pump, the Ideal scanner, for that is the GM tech to. There are Chinese knock offs available on eBay, search a thread on here from @THEFERMANATOR talking about it. OBD2 interaction and control with most other scanners are going to prove horrible results as this system was engineered in 1992 when they were trying to learn how to properly design OBD2 systems- the test puppy.
Hopefully THEFERMNATOR can have input about your issue- his transmission information is top shelf.

Your drain line from the FFM (fuel filter manager) is disconnected that goes to the water in fuel drain. Pictures are a good thing- post as many more as you can so we can keep an eye out for more things that slip past others not used to this unusual engine.

Can’t identify what turbo it is, but other than a GM “x” (as in GM4, GM5, GM6, GM7, GM8) any of which will do better to be replaced long-term with a larger turbo not just for added power, but increased fuel, mileage, and longevity. An hx40 is good example for that rig. Looks like the boot is torn on top, keep an eye on that.

The pmd looks still mounted to the ip - read about relocating it out of the engine bay and having a spare mounted. The common action is removing your existing one and making it the spare. Buy a new lifetime warranty one and run it both on heat sinks and put a dummy plug into the spare to keep contact pins clean. Whenever anything goofy is happening the pmd is highly suspect, often the cause. Leroydiesel.com sells them as kits and individual.

Get a fuel pressure gauge tap on the injection pump- modmafia.com sells them. Mount a permanent gauge in the dash. Anything below 2psi is hurting the injection pump, into vacuum is damaging it very quickly. Desired pressure is 8-14psi.

Replace the ip fuel return line with clear. It is a 1/4” diameter hose about 5” long in an arc- and upside down “U” shape. Fuel-line.com sells it by the foot. Watch that for air intrusion (air bubbles) flowing. A small trapped bubble is normal but not the flow of any. You can also see any contamination that goes through for diagnostics. Make the clear hose a permanent thing, monitor for more frequent replacement than normal fuel hose.

The original fuel hose doesn’t withstand modern diesel fuel well. Any other hose replacement should use sae30r9 or greater and shouldn’t be ethanol rated.

Be sure to add a fuel lubricant like Stanandyne or 2stroke oil. The lowered sulfur content diesel causes wear in the ip and injectors without it.

Learn about oil cooler hose replacement- harmonic balancer & drive pulley replacement-
Both engine killers.

Overheating is the #1 engine killer.
200f is ok
210f watch the gauge more than the road
220f pull over and let it idle back to normal.
Many sources including US Military says 230 and even 240 is ok- but they replace engines at 30,000 miles or less all the time.

Learn about the balanced flow cooling system- never add the “rear head cooling kits”.
 
OK, you have a DS4 injection pump, the Ideal scanner, for that is the GM tech to. There are Chinese knock offs available on eBay, search a thread on here from @THEFERMANATOR talking about it. OBD2 interaction and control with most other scanners are going to prove horrible results as this system was engineered in 1992 when they were trying to learn how to properly design OBD2 systems- the test puppy.
Hopefully THEFERMNATOR can have input about your issue- his transmission information is top shelf.

Your drain line from the FFM (fuel filter manager) is disconnected that goes to the water in fuel drain. Pictures are a good thing- post as many more as you can so we can keep an eye out for more things that slip past others not used to this unusual engine.

Can’t identify what turbo it is, but other than a GM “x” (as in GM4, GM5, GM6, GM7, GM8) any of which will do better to be replaced long-term with a larger turbo not just for added power, but increased fuel, mileage, and longevity. An hx40 is good example for that rig. Looks like the boot is torn on top, keep an eye on that.

The pmd looks still mounted to the ip - read about relocating it out of the engine bay and having a spare mounted. The common action is removing your existing one and making it the spare. Buy a new lifetime warranty one and run it both on heat sinks and put a dummy plug into the spare to keep contact pins clean. Whenever anything goofy is happening the pmd is highly suspect, often the cause. Leroydiesel.com sells them as kits and individual.

Get a fuel pressure gauge tap on the injection pump- modmafia.com sells them. Mount a permanent gauge in the dash. Anything below 2psi is hurting the injection pump, into vacuum is damaging it very quickly. Desired pressure is 8-14psi.

Replace the ip fuel return line with clear. It is a 1/4” diameter hose about 5” long in an arc- and upside down “U” shape. Fuel-line.com sells it by the foot. Watch that for air intrusion (air bubbles) flowing. A small trapped bubble is normal but not the flow of any. You can also see any contamination that goes through for diagnostics. Make the clear hose a permanent thing, monitor for more frequent replacement than normal fuel hose.

The original fuel hose doesn’t withstand modern diesel fuel well. Any other hose replacement should use sae30r9 or greater and shouldn’t be ethanol rated.

Be sure to add a fuel lubricant like Stanandyne or 2stroke oil. The lowered sulfur content diesel causes wear in the ip and injectors without it.

Learn about oil cooler hose replacement- harmonic balancer & drive pulley replacement-
Both engine killers.

Overheating is the #1 engine killer.
200f is ok
210f watch the gauge more than the road
220f pull over and let it idle back to normal.
Many sources including US Military says 230 and even 240 is ok- but they replace engines at 30,000 miles or less all the time.

Learn about the balanced flow cooling system- never add the “rear head cooling kits”.
Thanks. Some great info on the engine here.

Very few L65 engines in the UK as well, so the info is greatly appreciated. I'll definitely need to do the oil cooler hoses, since running the RV, I noticed one has started weeping, so will get that done ASAP.

I'll definitely grab one of those clone tech tool 2s. Is there anything I need to look for specifically? Looks like they take modules withe vehicle info on? All the ones I'm seeing are Opel/Saab, but nothing specifically GM or Chevrolet.

The transmission is the main thing holding me back at the moment. I'm going to grab an internal loom and temp sensor, only costs £40 delivered from the States, which isn't much at all. I'll drop the sump again and test the sensor internally and the resistance back to the plug and replace whatever component isn't working as it should. Hopefully someone else can shed some light on my issues.

I'm a big fan of keeping vehicles on the road, so will no doubt, get the hx40 turbo and the other mods you mentioned done too.
 
Thanks everyone so far. Learnt more in 3 days from you guys, than I had in months of researching for myself.

Came across this forum by chance and the info has been top notch so far.

Biggest challenge I'm going to have is the lack of knowledge in the UK, it means no-one will touch the mechanical work, or price it out the park and do a poor job anyway.

I was a mechanic by trade, so I can do the work fortunately, it's just knowing the vehicle and having the time!
 
On the HX40 turbo, you want to make sure it never goes over 12 psi of boost pressure without head studs. you'll also need to install a EGT gauge to watch exhaust temps.

for the CKO GM tech 2 they will work find but never try to update them. they will brick if you attempt updating the software. they will do lots of other vehicles besides GM.

just my 2 cents. fix all your issues before upgrading any parts. once it's all working as it was from the assembly line, then you can play with the upgrades. :)
 
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