P0894 for trans - Power is way off and runs horrible

[Gearheadvr4]

Trailblazer died at a light and after restarting it pulled a p0894 code. Engine power was off and idle and running was horrible. Felt certainly like a misfire but the code is pointing to the trans? Any ideas?


Have had a random misfire code P300 for a while but couldn't track down what the issue was. It ran fine and code wasn't consistent. Not sure if it's related to the p0894.

 

[Mounce]

Let's start with some background questions.

1. How many miles you got?

2. Checked transmission fluid level?

3. What color is the transmission fluid?

4. Was the fluid changed when you reached 100k miles? (if you're over 100k)

 

[Gearheadvr4]

1. 180k
2. It's high. We had a small leak about 10 app and I changed the pan gasket and added half a quart to much
3. Bright red since it was just changed but before it was kinda brown
4. I got it at 160k and don't know the history but I'd say it s maintained OK since we've had no issues other than the p300 code.

It is a 4x4 and doubtful the smurf fluid had been changed in the transfer case. But we've never tried 4x4 for that reason.

 

[The_Roadie]

I dont' have much to add on the other issues, but a dry/dead/damaged transfer case can make it undriveable in 2WD as well. Also the differentials are critical to get changed, since parts spin in the front diff in 2WD mode. And the splined disconnect on the passenger side front can deteriorate and the bearing could die and then the CV shaft wobbles about and can clank itself to death.

Just a reminder that using 2WD alone doesn't mean you can ignore the 4WD system parts.

 

[Mooseman]

The transfer case would have nothing to do with the P0894. I found this and the news ain't good:
http://engine-codes.com/p0894_chevrolet.html

Possible causes

- Low transmission fluid level
- Dirty or contaminated fluid
- Internal transmission failure



When is the code detected?
When the Powertrain Control Module (PCM) detects excessive Torque Converter Clutch (TCC) slip when the TCC should be engage, then the trouble code P0894 is set.

P0894 Chevrolet Description

The Powertrain Control Module (PCM) monitors the difference between engine speed and transmission output speed. In D3 drive range with Torque Converter Clutch (TCC) engaged, the engine speed should closely match the transmission output speed. In D4 drive range, with the TCC engaged, the TCC slip speed should be -20 to +50 RPM.

Either your TCC is slipping or the internal clutches are slipping. If your fluid was brown/burnt before the change, it may already be too late. It could also be something as simple as the TCC solenoid. I think it's time for a consult with a tranny shop.

 

[Gearheadvr4]

I don't trust any transmission shop. Many bad experiences with that. If anyone can point out where the TCC solenoid is I'd like to swap that first before going to a shop.

 

[Mounce]

It's inside the transmission so you'll have to drop the pan again. I believe it's directly accessible once the pan is dropped though so you don't have to dig to deep.

Do some googling or searching here about it, a lot of people swap it out with a different one so that it's no longer PWM actuated IIRC.

 

[Mooseman]

While looking for the solenoid, found this video:

https://www.youtube.com/watch?v=5Jeb0KpAN_g

At 2:20, it says that if you're getting a TCC performance code, then it's not the solenoid and the TCC itself is likely at fault or a blocked passage, which means dropping the tranny. If the TCC was slipping, it would support the reason why the fluid was burnt.

 

[DAlastDON]

If the torque converter is not completely disengaging...Could that be the cause of the crappy idle?

 

[Gearheadvr4]

I've done some searching also and cannot find where it's located. All the selinoids looks the same.

 

[Gearheadvr4]

Maybe I've been going about this the wrong way. I cleared the codes and the trans slip code has not come back. Possible that it kicked out that code when the truck died at the light? That's the only time I've ever seen that. Plus the trans works fine otherwise.

Also the p300 misfire has been a nagging issue that I couldn't track down. It's always idled rough but ran OK. If the coil pack did finailly die would that cause the truck to shut off and then rough running?

 

[Mounce]

No you'd just have a bad idle. There's six of them so it'd still run 5 cylinders, just would run good.

-it really shouldn't cause it to die though

 

[Gearheadvr4]

Got a better scanner an it said a bad coil to cylinder #1. Going to start with that first and still hoping nothing wrong with trans.

 

[Mooseman]

If you can get a way to read live data (ELM327 and Torque would work), you could see which one is misfiring most and start there.(Just saw you already did this) Don't run it too long like this or you'll cook the cat.

For the TCC solenoid location, found this which is very good. The forum is in French but the pics are English:
http://www.hummerbox.com/t1371-schema-et-emplacement-composants-electriques-et-des-solenoides-de-la-boite-automatique-gm-4l60e

If the TCC was staying engaged while idling, it could make it stall. The valve body could be worn or blocked or something. I know there is a specific valve that has a tendency or wearing out and causing problems but can't remember exactly what.

I also found some more info here:
http://www.ebay.com/gds/PERFORMANCE-VALVE-BODY-REPAIRS-IN-A-4L60E-TRANSMISSION-/10000000008336495/g.html

THE OTHER MAIN PROBLEM AREA IS THE TORQUE CONVERTER CLUTCH (TCC) REGULATOR VALVE AND VALVE BORE. THIS VALVE REGULATES TCC APPLY PRESSURE. THE TCC VALVE BORE USUALLY WEARS EXHAUSTING APPLY PRESSURE AND DIMINISHING LINE PRESSURE. THIS IS THE PRIMARY CAUSE FOR THE 1870 TROUBLE CODE AND OVERHEATED CONVERTERS. ANOTHER COMPLAINT FROM THE CUSTOMER IS THE TORQUE CONVERTER "GOES IN AND OUT OF LOCKUP" OR THE VEHICLE FEELS LIKE IT SURGES AT HIGHWAY SPEEDS.

Now this could very well be the cause but if the TCC and/or tranny are already borked, then you're throwing good money at a bad tranny.

 

[Gearheadvr4]

Thank you for the info on the trans. I'm holding off on messing with that for now.

It was odd that the Torque app didn't see the P0301 when the shop scan tool did. It's possible that it just hadn't migrated from the P0300 yet. I know from other forum posts that the random shows up usually before the ECU nails it down.

Swapped out coil #1 and all is well. It's back to the way it was running before. Idles a tad rough but runs like a champ again. While im in here I'm swapping out the plugs to the AC Delco Irudiums, cleaning the maf and throttle body, and checking all other fluids.

As a side note I'd still like to track down the slightly rough idle. I suspect I'll get a p0300 again soon. How would I track down the other coil (if it is a coil) that could cause it to run rough?