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2003 Forester XS w/Premium Package and 5MT tranny
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Discussion Starter · #1 · (Edited)
Our Chevy truck has a strange issue, as described below:


When I started our 1994 Chevrolet K1500 Silverado Z71 4WD pickup one day in September 2017 to take a load of trash to the dump, the Service Engine Soon (equivalent to Check Engine Light in today’s vehicles) dashboard light was illuminated. When I shifted from Park to Reverse, there was a physical and audible jolt, and the front left corner of the hood visibly popped downward about an inch or so.

As I began driving, it was very hesitant to upshift or downshift. When I got to the stop sign that’s 7/10ths of a mile from our house, it was refusing to accelerate from a dead stop. In fact, it would barely move forward as I pressed the gas pedal, and it sounded like the engine was about to die. It continued to do this until I chose to shift it into first gear manually. There was then another noisy, severe jolt. It remained somewhat hesitant to shift from one gear to another despite my shifting the tranny manually.

I continued to shift the transmission manually partway to the dump until it finally began shifting easier in Drive, albeit hesitantly. I made it to the dump without stalling the engine. When I started the engine to leave the dump, the Service Engine Soon dashboard light was off, and the transmission again shifted normally in Drive.

I’m afraid that this could mean that our truck’s transmission is on its last leg. Is this possible? Or could it be a weird electrical/computer problem that is causing this issue to occur while simultaneously illuminating the Service Engine Soon dashboard light? Now that I think about it, I remember that this issue has happened twice before today, with self-resolution occurring after driving somewhere, turning off the engine, and starting the engine again to come back home. More recently, our truck engine stalled when I attempted to accelerate from a stop.

Also, even when the Service Engine Soon light isn’t illuminated, our truck’s transmission is not the smoothest-shifting transmission.

Does anybody here have any ideas what could be causing our truck’s transmission issue?


I did more recently read that, based on our truck’s symptoms, its transmission could have a worn TCC (torque converter clutch) regulator valve.

Following are the symptoms of that issue:

1. Service Engine Soon light is on (intermittently)
2. Harsh-shifting from 1st to 2nd gear (and other gears)
3. Engine stalls from a stop at times, due to engagement of TCC (similar to a clutch in a manual tranny)
4. Code 1870 is stored on the computer, which indicates internal slippage

Our truck exhibits all of the above symptoms, except that I don’t have an OBDI scanner to check that the code is indeed #1870.


December 2018 update: I drove our truck to the dump yesterday, and it stalled from a stop twice. That makes me nervous to drive the truck at all until we can fix its tranny issue. It's definitely a safety concern because one of the times it stalled was as I slowly making a turn onto a road that has a 45 mph speed limit. I was in the middle of the road when it happened. Thankfully, I used the truck's momentum to carry me across the road to someone's driveway. Then I was able to safely restart the truck's engine.


One friend of mine with mechanical knowledge suggested that I replace the tranny with one from a local pick-and-pull junkyard. I’m nervous about doing that because a used transmission could have the same issues as our truck’s current transmission.

Another friend of mine who’s been a Subaru mechanic for over 20 years believes that our truck’s transmission probably needs to be rebuilt. I think that’s not a bad idea, except that the cost may be prohibitive. I’m trying to discover the cheapest, most cost-effective way to fix our truck’s transmission.

With that in mind, I found what looks to be a website with beneficial information about fixing our truck’s transmission (GM 4L60E 4-speed automatic transmission): Transmission Bench

The above site has info on fixing a worn TCC regulator valve, as well as the parts and tools needed to do so. Including the fluid, filter, and gasket that I’d inevitably need also to purchase, that repair would come to about $288.72.

That site’s owner also has a YouTube series (HD) with 18 videos (7.5 hours) of content about rebuilding the GM 4L60E 4-speed automatic transmission.

He also sells a kit for the GM 4L60E which appears to include practically everything needed to rebuild that transmission for $400, with free shipping.

Based on his ‘About Me’ page, he seems to be very knowledgeable about and experienced with rebuilding several automatic transmissions found in American vehicles.


What do y’all think I should do? Any ideas?


Thanks!

Caleb Lewis
 

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2019 Sport cvt
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154 Posts
I had a 1994 1/2 ton 4x4 Chevy. Z71. They had to replace the transmission at about 25K miles for a continuing series of tranny problems. Under warranty but the last time it cost them a lot to Fed Ex one overnight from Texas to Ca. No real problems after that. But that was 20+ years ago. No suggestions, just sympathy. My understanding is that of you sart changing fluid, etc., you'll likely soon need serious trans work so depending on the miles, likely a rebuild is in your future?
 

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2010 Forester
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66 Posts
Stalled at 45 mph? Doesn't match the trans problem you describe.
"Service Engine Soon dashboard light was off, and the transmission again shifted normally in Drive."
It sounds like an intermittent issue.
Broken mechanical things don't heal themselves.
Go to any auto parts store and they can read the code.

No reason to replace the trans until you are sure.

I have a 2010 with the same trans.
If you don't rebuild it, change the fluid to MAXLIFE.
 

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2003 Forester XS w/Premium Package and 5MT tranny
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44 Posts
Discussion Starter · #4 ·
I had a 1994 1/2 ton 4x4 Chevy. Z71. They had to replace the transmission at about 25K miles for a continuing series of tranny problems. Under warranty but the last time it cost them a lot to Fed Ex one overnight from Texas to Ca. No real problems after that. But that was 20+ years ago. No suggestions, just sympathy. My understanding is that of you sart changing fluid, etc., you'll likely soon need serious trans work so depending on the miles, likely a rebuild is in your future?
Wow... Our truck had over 250K miles on it before it started having this tranny problem. Your truck having only 25K miles on it when it began having tranny problems seems like an anomaly compared to how long GM trannys usually last before they begin having issues.
 

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2003 Forester XS w/Premium Package and 5MT tranny
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44 Posts
Discussion Starter · #5 ·
Stalled at 45 mph? Doesn't match the trans problem you describe.
"Service Engine Soon dashboard light was off, and the transmission again shifted normally in Drive."
It sounds like an intermittent issue.
Broken mechanical things don't heal themselves.
Go to any auto parts store and they can read the code.

No reason to replace the trans until you are sure.

I have a 2010 with the same trans.
If you don't rebuild it, change the fluid to MAXLIFE.
I went back and edited that section of my post to clarify the details. Specifically, that road has a 45-mph speed limit. To further clarify: I wasn't driving at 45-mph when making that turn.

Our truck's tranny issue has been intermittent, to be sure.

No, indeed. I know our truck needs some serious TLC to fix the tranny issue. However, I'm not sure that we have the amount of money needed to pour into such an issue right now. Plus, this truck is only being driven once a week right now anyway (to go to the dump).

I may bring our truck to AutoZone at some point to see exactly which code is being thrown. The only problem with doing that is that the Service Engine Soon light isn't on all the time; it is very intermittent.
 

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2012 Forester X Auto
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2,512 Posts
I may bring our truck to AutoZone at some point to see exactly which code is being thrown. The only problem with doing that is that the Service Engine Soon light isn't on all the time; it is very intermittent.
The code should be still be stored and can be retrieved whether the light is on or not.
Most vehicles store error code history that remain until the error code gets deleted.
 

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2018 Subaru Forester XT Touring
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25 Posts
What does your post about a Chevy truck have to with a Subaru Forester forum? Just asking since it seems out of place.
 
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