Truck randomly dies when braking

About a month ago my truck shut off while i was braking kinda hard and i thought i had just forgot to take it out of gear or something. Then 3 days ago it happened to me again same situation but i know the clutch was in. And again coming home from work today. It doesn't shutter or anything when it dies the rpm's just drop to 0 and the only way i really tell is because braking gets harder because no vacuum. I try to duplicate it and can't its just at random. Any ideas?

Only thing i have messed with recently was my long travel install which i only pulled the front diff to regear and longer brake lines then bled brakes. The first time it happened was the day after my front end was installed after the truck had been sitting in my garage for a month.

 

A defective neutral safety switch may be the cause. It's attached to the clutch so that you can't start the truck in gear. If it's starting to go bad it could be causing the truck to stop running when you push the clutch in.

Good Luck,

AL

 

dirty maf can stall motor at odd times
worn (old) tps can do it too....

check it and if not perfectly sparkling clean, clean it

 

Are you throwing any codes? I've had a similar problem when my EGR valve on an older GMC was getting stuck with carbon. I took it off and cleaned it a few times, kept happening so I grabbed a screen from a faucet aerator and fit it in there, never had the problem again. What I would get is when I hit the brakes kind of hard it would feel like I lost power brakes and stall the engine.

 

Break booster?

 

MAF was dirty, cleaned it and happened again. No codes, just dies. Also vacuum lines on brake booster look fine.

 

Low oil?

 

What year is the truck? Also, have you run through a full tank since the front end install? My initial guess is bad gas. The truck sat for a month and ethanol absorbs water. Too much water in the fuel would cause the truck to stall at low rpm. If still the same tank, pour in a bottle of dry gas and fill 'er up with no E premium.

 

Wanna share how this works?

 

While I'm doubtful the braking system has any role in this, it's pretty easy and free to check out, regardless.

http://www.classicperform.com/TechBo...tm#testbooster

Any chance your fuel is so low that the pickup goes dry (cavitates) just long enough to create a stall, ie 'out of gas'?

Any chance you have bad gas? Sitting a long time? All your issues on the same tank, or have you filled up in between incidents?

 

does it die when you go over bump ?! if so look the ground i had a old chevy doing that and it was a faulty ground

 

Try cleaning your throttle body as well. Had that same problem with a nold truck I use to have, I cleaned the maf and throttle body and it never happened again

 

This would be the first thing I would try. Start with a simple cause, and easy remedy and go from there.

 

It sounds like your brake booster is robbing vacuum.

 

Oil is not low, not all on the same tank of gas, truck is an 2005 trd sport, no gas is not low.

Did it to me again twice yesterday.

 

link doesn't work

 

Not much help but my 05 did the same thing to me many years ago. Hit the brakes hard to pull into a rest stop off the highway, pushed in the clutch and it just went dead. Started right back up afterwards. Has happened a few times over the years but not as often as yours. My rpms will drop to almost stall on hard breaking but the computer seems to catch it most times and it recovers in a few seconds. I now have 240k mi and it still runs well, just one of those fluke things.

 

http://www.roadkillcustoms.com/hot-rods-rat-rods/hot-rod-power-brake-booster-test.asp#axzz3X92m1qNk
Did those tests and they were all good, pedal goes down more than 1/4'' though, and booster vacuum line and check valve are good too.

 

I'd put a vacuum gauge on and run the line to into the cab. It sounds like a vac leak in the Booster.

 

How old is the battery, how are the connections?

If you're braking hard enough for the ABS pump to engage, with a weak battery or poor connection, and the engine at idle, the system voltage may be dropping below what the ECM requires to keep the engine running.