4L60E issue

[RMcbride]

Hey all first post here, thanks for any help with this. 99 1500 Suburban 4x4 with auto TC. Just bought cheapish, been neglected and am trying to address all it's issues. Main thing is, i'm getting a hard TC lock up... it's abrupt like the PWM isn't working. I did new DexIV and filter, and some platinum lubegard, it did help. Sometimes it doesn't "do it" at all, but sometimes it will do it frequently, usually with little load, and it might do it a couple times... in/out. Will be taking it somewhere soon to be scanned and driven by trans specialist, but was surprised on the phone when he said he hadn't heard of this problem before? Anyway, wondering if replacing the harness and two selenoids might be indicated here. I'd suspect that someone did a PWM delete except for sometimes, it works. Thanks

[dtnel78]

PWM delete?

You can have it scanned at a autozone for free and see if you have any codes to see if that can give you a direction before you take it to a transmission shop and plunk down a bunch of money for something that could be simple? Have you checked the wiring harness, check for any corrosion at the connection points, check for any corrosion hooking up to the transmission ECM? It could be something simple such as one of those or you just clean it up real good and put some good proper lubricating grease on it design for electrical contacts.

On a side note whenever I get a vehicle that's used that I plan on keeping for personal or family use I generally run it down to the transmission shop, have them drop the pan, service it complete, take it for a test drive and let me know of anything else that they see or feel is wrong before I put it on the road. I don't want to be stranded and I don't want any members of my family stranded. Most often when I do this I find that liver had the vehicle before me didn't take care of the transmission as it should have been. These Transmissions these days are finicky even down to the type of transmission fluid you need to use and that varies from manufacturer to manufacturer. I do know mine always get synthetic in them because that's what the transmission shop uses. Definitely drop us a line and let us know what you figure out what the transmission shop unless you figure it out before then. It's good to hear back that way we have reference material to fall back on at times. Have a good day!

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[RMcbride]

Well, since one bottle of lubegard "helped", I put another bottle in and drove it a few miles and during that time it didn't "do it" even once. Just about to go try it again and see if my "fix" holds. Yes, it's possible it's an electrical issue, but I think more likely it's just had evil fluid in it for so long the pwm sel. suffered, and whatever's in that lubegard is brining it back to life lol. Yes believe me when I buy a used car I don't stop till it's functioning mechanically as new. Grandpa was a union diesel mechanic, still have his tools and I feel thankful for that most every day that passes. 

[Black02Silverado]

I would have tried changing out all the fluid.  If it was contaminated it could have caused the issue.  Putting in additives to me is a band aid.  Which looks like what you are wanting anyway so I guess why not. 

 

How many miles are on the vehicle? 

[pronstar]

Well, since one bottle of lubegard "helped", I put another bottle in and drove it a few miles and during that time it didn't "do it" even once. Just about to go try it again and see if my "fix" holds. Yes, it's possible it's an electrical issue, but I think more likely it's just had evil fluid in it for so long the pwm sel. suffered, and whatever's in that lubegard is brining it back to life lol. Yes believe me when I buy a used car I don't stop till it's functioning mechanically as new. Grandpa was a union diesel mechanic, still have his tools and I feel thankful for that most every day that passes. 

I do the same with my used vehicles...including my 99 Suburban, too LOL

Rebuilding the front end did wonders for the steering, BTW [emoji106]

Wasn’t too thrilled about rebuilding the tranny, but I lost all but first gear so something had to be done LOL


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[RMcbride]

Black02Silverado yes, thanks that was the first thing I did. Ran 5 gallons of Valvoline Dex VI through it and a wix filter. Drove it again and it's functioning perfectly, knock on wood, or something like that. Also did the same with the PS fluid plus LG's power steering whatever it is additive, rear diff bearings, wheel bearings and seals all new brakes, bilsteins, all new fluids diff/TC case tune up parts tps iac heater blower/resistor door handle led turn signals hyperflash relay headlight bulbs u-joints alignment all new brakes reset z height/trim, think that's it for now and I don't know why my text is orange lol.