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Cobalt Transmission problems... I think?
08-04-2014, 12:30 AM
Post: #11
RE: Cobalt Transmission problems... I think?
I am kind of skeptical of if the transmission was ever really low. I have read post #4 over & over and it sounds to me like the transmission wasn’t slipping when it went in for service. If it was over 4 quarts low it SHOULD have been slipping going TO the shop. Then they added a bunch of fluid and the transmission slipped on the way home. It did that for two days and then it quit slipping. It sounds to me like the shop might not have known how to check the transmission & added way to much oil. The transmission slipped because it was flooded? After driving for a couple of days it blew out enough fluid to start working again?

No matter what the situation, I agree that it needs checked out. I just think that it needs to go somewhere else and get a second opinion. The transmission could now be covered in fluid making it look like a leak & it might not even be from a leak. It could just be blowing out the vent. What do you think, Rupe? If nothing else, read the owners manual, learn the proper way to check the fluid, & then check it yourself. If it’s not low it’s probably not leaking but I’d still check it a couple more times in the next few weeks while also watching for drips where you park it.

Thanks for using the forum,
Garner

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08-04-2014, 01:59 AM
Post: #12
RE: Cobalt Transmission problems... I think?
I agree Garner! Even though the other problems, from my initial post, were still present before they added the fluid, I thought it was weird that the transmission didn't slip until after. I can't get under there myself and it's hard to teach my son without actually being under there to show him what to look for. I can understand the reasoning behind an enclosed system, but when something goes wrong, I miss the dipstick! I'm going to get him out there tomorrow to check all the connections. If everything seems secure, I'm going to order the ECM. Will keep you updated.
Thanks again,
D
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08-04-2014, 09:31 AM (This post was last modified: 08-04-2014 09:35 AM by Rupe.)
Post: #13
RE: Cobalt Transmission problems... I think?
Here's the problem that started this mess... there's no dip stick so you must follow the book. Too little fluid and it will slip. Too much and it will foam up. I don't believe this is in the owners manual but it is in the various shop manuals.

To check the fluid in the trans, there is a 11mm headed plug near where the passanger side axle goes into the transmission. What you do is, after you replace the pan, put almost 7 qts of transmission fluid in the fill cap on the top of the transmission. Start the car, warm it up and run it through the gears several times. Then remove that 11mm headed plug while the engine is running with the transmission is in park. If fluid runs out of the plug, allow it to drain until it becomes a constant drip. Put the plug back in and you are done. If fluid did not come out of the whole, start adding fluid to the trans until it starts to drip, then reinstall the plug. They hold 6.9 quarts of Dextron synthetic. (Dex VI?)

Edited to add: Crack that plug with the engine cold and off. That way it's easier to get it out with your fingers when warm. If you pull that plug with the engine off several quarts of ATF may drain out. Also, when sticking that plug back in don't snug it too tight. A cold plug and a hot case will make for it being WAY too tight next time.
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08-09-2014, 08:42 PM (This post was last modified: 08-09-2014 10:31 PM by dplusm1995.)
Post: #14
RE: Cobalt Transmission problems... I think?
I'm holding my breath that I missed a step! I got the ECM in today and replaced it. The car started up fine after the security relearn procedure, but the engine light is still on and all of the problems are still there. Going back over my posts, I realize that I left out a symptom and I'm hoping it's not a game changer. Since these problems started, the transmission jerks with a thud when the gear shift is moved from park to reverse. Is it possible that the car is in the same limp mode, and will be until I complete the Crankshaft Relearn Procedure? But would there still be a thud when the transmission is moved from "P" to "R"?

I guess the big question is, if there is a problem with the actual transmission, would it have shown up on the Tech II scan? I will get to Advanced Auto this evening or tomorrow and run another code check. Maybe I will get lucky and the only code that pops is the P1336.
Thanks Guys,
D

UPDATE: Just got back from Advanced Auto. The only code that set was P0604.
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08-10-2014, 12:30 AM
Post: #15
RE: Cobalt Transmission problems... I think?
Here's the problem with going strictly by the codes. You have to address the codes as they appear. Unfortunately sometimes we (and everyone else) jump the gun on what appears to be the obvious but we haven't solved the first few to see if the others clear up.

Let us know where this goes.
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08-10-2014, 09:52 AM
Post: #16
Cobalt Transmission problems... I think?
Also; going along with addressing codes as they appear, I worry about getting the codes from a parts store. Most of them only have low end scanners that won’t access all of the systems. In that case, you could only be seeing a code that is a symptom of another system.

I also don’t know how good a job was done in checking the wiring harness, connections, & fuses. P0604 could be caused by a blown fuse, loose connection, corrosion, shorted wire, etc. Here’s the link to some information on that code again:

OBD-II P0604

Here’s something to think about in lines of what Rupe is trying to make sure doesn’t get passed over. You have to weigh all things together, think, & don’t skip over the tedious work hoping for an easy fix. So what about that “Bump” from Park to Reverse? Could you have a bad motor mount that is letting things move around to much? Could the extra movement pulled some wires apart, rubbed them through, got them up against the hot exhaust...? “Harness Open or Shorted” can involve a lot of things. Probably the easiest way to check would be to have a wiring diagram so you know what wires feed power & ground to the PCM. Start at the PCM & check for power & ground there. If you don’t have both, you can start following the harness back until you find the problem.

I think that would be where I would start if I was doing that job. Confirm power & ground at the PCM. If you have both then move on to other possibilities. Something to think of then would be, “Is there a breaker or relay on the main power circuit?” I have see vehicles that had that set up. I would check for power at the PCM, it was there, but when I checked codes after a test drive it said that I lost power. Then I had to check for a weak breaker or relay, intermittent short, or intermittent open. That could also lead back to a bad mount letting things move.

I hope that gives you some ideas. Please keep us in the loop.

Thanks for using the forum,
Garner

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08-10-2014, 10:03 AM
Post: #17
RE: Cobalt Transmission problems... I think?
To add something on top of Garner's post, let's not overlook the simple stuff. Could that "bump" be a too fast idle speed?

Also, given a replacement ECM you may want to have it cleared then start from scratch on the codes. I have seen one or two actually set a code on removal or installation because someone didn't disconnect the battery and it's impossible to get all of those plugs / pins to make contact at the same time. IOW, there's always going to be something disconnected when it powers up that way.
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08-10-2014, 03:16 PM
Post: #18
RE: Cobalt Transmission problems... I think?
Again, thanks guys. You've given us a lot to look at. Rupe, I disconnected the negative terminal before I replaced the ECM; was that correct or should I have disconnected both? I had a friend check the mounts and he said the back motor mount did look weak, which might explain why it shifts harder from "P" to "R", than the other gears. He also said I might need to hit the interstate and stay above 60 for around 10 miles. Something about retraining the overdrive??? When he drove it, he pretty much said the same thing. It seems like the car is starting in 2nd, immediately shifts to 3rd after a couple seconds and then never shifts again.
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08-10-2014, 05:32 PM (This post was last modified: 08-10-2014 05:34 PM by Rupe.)
Post: #19
RE: Cobalt Transmission problems... I think?
Disconnecting one or both cables works.

You can't always see much just by looking at the mounts. I usually stand to the side and visually watch for excess movement of the engine. That way you can see the mounts under load... and again, if the idle is too high then it will bang / bump anyway.

There is a quick-learn process you can do with a fancy scanner but if you have already driven it that part should be set.

At this point you need someone with a full function scanner who knows how to go in and look for shift commands from the ECM to the trany. If there's no tach in the car the scanner also has the ability to read RPM.

BTW, about a year ago I had a vehicle driving me nuts because it would always start in second gear. The rest of the gears and OD were there, just no first gear. A full function scanner found the issue and pointed to the ECM. Without the scanner I would have no way to find that info. In my case I started with pulling the pan (high miles) and it was clean as a whistle.
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09-26-2014, 10:00 PM
Post: #20
RE: Cobalt Transmission problems... I think?
I know it's been a while but here's the update. We saved up some money and had a mechanic run a full-function scan... even running diagnostics while the car was being drove. In the beginning, he determined that the car was starting off in 3rd gear and not shifting properly. He said he was able to bypass the TCM using his diagnostic tool and the car shifted just fine. Final diagnosis was a faulty TCM.

Once the part came in and he was about ready to install and flash, he called to tell me that we needed to take a step back. He was stuck on the fact that his diagnostic tool was able to bypass the ECM and shift the car properly. He ultimately decided to recommend fixing the ECM instead. He sent the ECM off to some place that repairs any faults and rebuilds the module's circuits.

Here we are a week later with a rebuilt and reprogrammed ECM, but still have the exact same issues! Now I'm told once again that the TCM is faulty and now it needs to be replaced!!! Does any of this make sense or is it just time to invite all the neighbors to a big ole' cobalt bonfire!
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