Trans... break! 4l60e

[JNJchev77]

Daily driver was low on fuel, so I decided to take the truck to work this morning.

Cruising about 65-70mph on the highway and then all the sudden it revs weird and down shifts, then down shifts again. Luckily I was able to safely pull over as there wasn't much traffic. I slowed to about 25mph and was able to keep moving to the off ramp. Then the truck shut off?!

Fire's right back up and moving again. As I'm heading back home I decide to give it some gas, get up to fourth gear and it's fine for a few seconds, then the same thing happens. Truck accelerates fine through the gears...

I notice when I hit a significant bump in the road that's when things kind of go haywire with the shifting and I can hear some minor clicking/clunking coming from the trans tunnel area. I was able to limp home, but haven't been able to scan anything yet... Any ideas? Did I lose the tranny??

Here are some specs:
'03 5.3 with Z06 cam/springs
Aftermarket Computer - Street tuned by local shop
4l60e was rebuilt by AAMCO, stock rebuild - mileage is exactly 1000.
I replaced the harness in the trans along with the 1-2 shift solenoid a couple hundred miles ago and haven't had any issues up until now.


I had a shift problem in the past that was a fuel related issue, but have since solved that issue. The truck would not shift from 1-2 at WOT because it wasn't getting enough fuel. Bad pump and clogged line were the culprits.

[JNJchev77]

Thinking back, that clicking sound could have been electrical. My computer and relays are under the dash... I will check relays, fuses and grounds.

[Alex41]

I had one do this a few times to me. It turned out to be the servo on the side of the case. The o ring had slipped and was bleeding off pressure.

Def. check the clicking relays first tho. Good luck and keep us posted.

[JNJchev77]

Originally Posted by Alex41

I had one do this a few times to me. It turned out to be the servo on the side of the case. The o ring had slipped and was bleeding off pressure.

Def. check the clicking relays first tho. Good luck and keep us posted.

Ok, I'll keep that in mind. Was it leaking from the servo?

[homemade87]

Your trans should not shut your engine off . Those relays could be the culprit . Sounds like you are loosing your power supply to your system . My guess from what you are telling use that you have an electrical problem . Most likely your trans is ok. Sounds like the pcm was loosing power intermittently which will cause the trans to do weird things .

[BR3W CITY]

It probably hits and cuts the current, so it tries to LIMP itself. When you restart, you clear the limp and go again.

[Bigdav160]

Sounds like it has set a code and defaulted to third gear

[Alex41]

Agreed that it shouldn't shut the engine off so electrical is probably the culprit.

No, there wasn't a leak from the servo when I had a problem. The o ring was bleeding pressure off to the inside of the trans....made it SUPER hard to figure out. lol

[JNJchev77]

Thanks dudes! I am going to check codes when I get home and check the fuse block.

I will let you know what I find and go from there!

[JNJchev77]

Originally Posted by Alex41

Agreed that it shouldn't shut the engine off so electrical is probably the culprit.

No, there wasn't a leak from the servo when I had a problem. The o ring was bleeding pressure off to the inside of the trans....made it SUPER hard to figure out. lol

Thanks, Alex

[LockDoc]

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I don't know what the symptoms would be if the main wiring connector plug was loose in the trans. Just thinking out loud here....

LockDoc

[JNJchev77]

Ran a scan through, nothing pointing to what's going on... P1638 & P0463...

Checked fuse block and relays, everything seems fine. Going to crawl under today and see if anything is loose, etc.

[BR3W CITY]

I'm just glad you didn't hot-side everything and fry the PCM.

[JNJchev77]

Originally Posted by BR3W CITY

I'm just glad you didn't hot-side everything and fry the PCM.

I got very lucky!

[JNJchev77]

Decided to take the truck on the 30 mile journey to work... Drove like a champ, no problems!! I did finally come up with a name, as every old truck should have a name right - "Sparky" kind of fit, so there you go ...