4l60e help!

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stutaeng

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P0785 – Shift/timing solenoid -circuit malfunction

How to Clean the EGR Valve for GM Code P1406

P1870 (Transmission Component Slippage

Mine does that hard shift from 1-2 (a bit less hard also 2-3 and normal 3-4) and throws a P1870. It only does it after I drive on the highway for about 10 miles and shift from a stop. If I shut it off and turn it back on it goes away, unless I drive highway again, etc.

My understanding is that the line pressure stays high and doesn't come back down as it should to shift 1-2. You need to hookup a line pressure guage to verify and the problem is the valve body. Rockauto sells a valve body for around $200, and then you have to do the work. YT videos show this but seems a bit involved. I called a shop and they quoted me $400-$500 to swap valve body.

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On this video they show exactly the issue. I may be wrong on the problem, or the pressure is a result of the slip code? Don't know.

So I think you may have this problem, AND a shift solenoid issue. The shift solenoid is easy, just have to drop the pan and you can check continuity with a voltmeter.

But if it is slipping on all gears, probably needs a complete rebuild?
 
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So I just decided to try out the truck 1 more time. Fired that bad boy up, put it in gear and it went with no slipping, I stopped in front of my house and did a burn out and keep goin thru 2nd and 3rd with no problems but only drove it about 1/2 mile. Soo strange lol but I know it would started acting up once it warmed up. I didnt realize 4l60e can be so feminine lol. Sucks there is no cheap fix either but I guess I'll buy a new valve body and then have it installed with the new rebuilt I'll probably end up doing
 
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Speaking of converters, I already bought a 1900-2100 light stall and I've installed a tranny cooler as soon as I picked up the truck. Are 4l60e's just problematic??? Is there a trick to longevity or something? I just wanna use this truck for a clean cruise that will tow my car to the track maybe once a month. Installing 3.73 gears to help with that over the winter along with a posi unit
 

df2x4

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Are 4l60e's just problematic???

Yup.

That said, the best way to keep one alive IMO is to keep it as cool as possible and don't touch the tuning. If your truck doesn't have a factory AUX transmission cooler in addition to the one in the radiator I would definitely add one.
 

stutaeng

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So I just decided to try out the truck 1 more time. Fired that bad boy up, put it in gear and it went with no slipping, I stopped in front of my house and did a burn out and keep goin thru 2nd and 3rd with no problems but only drove it about 1/2 mile. Soo strange lol but I know it would started acting up once it warmed up. I didnt realize 4l60e can be so feminine lol. Sucks there is no cheap fix either but I guess I'll buy a new valve body and then have it installed with the new rebuilt I'll probably end up doing

That was funny...no wonder you are having issues, lol. Just kidding.

Yes, you can get it rebuilt. In the situation I stated above, I can probably do an 80 swap for the same price of fixing my 60. Heck, the '95 80e I found was $240!

That's only if you do all the work yourself, of course. If you get a shop to do it would be easy $2000-$3000. If you are running big power numbers, that's equivalent to a "built" 60e. So in that case it doesn't make sense to do a 60. A stock 80 can handle more power than a beefed up 60 is what it boils down to...

In my case, I fell in love on the way the 80 shifts on my other trucks. Thing is silky smooth! I'm running stock engine and don't do burnouts, just occasional towing.
 
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Lol well the last time I drove the truck home i barely made it so I didn't have nothing to lose . I dont usually drive it like that, I have a built foxbody I pound on lol. But I'm goin to buy a new tranny or get this 1 rebuilt. It's a low mileage truck so I might as well. All of you guys are very helpful, i really appreciate that
 

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I changed both A and B shift solenoids and nothing changed at all lol. I'll fix egr after the tranny and I just wanna make sure nothing electrical went bad to cause the tranny to fail so that's y I'm trouble shooting before I remove it.
OK, so changing shift solenoids A & B wont have any effect as there is no indication that there is an issue with them. P0785 is for the shift timing solenoid ( or 3-2 downshift solenoid ) not the "shift" solenoids, and this occurs when the TCM sees the resistance in that circuit is outside of the preset parameters. Most commonly the solenoid itself but occasionally an issue with the circuit between TCM and solenoid connector. Check the solenoid resistance or just replace it - they're cheap, but address this fault first, clear codes and see how it performs . This fault is pretty much never an indication that you need to recondition/replace the trans. P1870 (component slippage) is a performance code that can occur for numerous reasons, often due to irregular performance of the torque converter clutch. Again not necessarily catastrophic . Often an upgrade to the TCC control valve will remedy this, but I'd still address the timing solenoid and then re-assess. EGR faults on some GM vehicles have been known to cause slip/ratio errors to be generated too. Maybe someone in your neighborhood (USA) can elaborate as to whether this is a possibility on your particular model with the 4L60E
 
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