Truck dies at idle with AC on

[TangoBravo]

So if my TB is at idle and I have my Ac on it will kill the enigne after about 3mins. Then it can be started right after however the CEL is on an will stay on for awhile then it's like it clears it's self and after about an hour or if you turn the truck off three or four times the CEL goes off. Any suggestions would be great. Thanks guys

[MrSmithsTB]

Does it run fine and just randomly cut off? Does it run rough and fluctuate in rpms before eventually cutting out? When is the last time you cleaned the throttle body?

[Trail X]

What's the DTC?

[TangoBravo]

I clean the throttle body often I would say every 60-80 running hours however since I have been using Amsoil it has never been as gunked as it used to get so I don't think that's the problem. Also it runs just fine no rough idle or fluxuation in rpms it just flat stops. It does not do this at all while driving only in park and at idle, We have gone wheeling and commute whith it and it has never just died unless it is in park and at idle.

@james I don't know what DTC is so I couldn't tell ya.

[Blackout]

The code. What is the code

[TangoBravo]

The code. What is the code

I am not sure, dont have anything yet to read my codes. It is on my list of things to get but as of now I have no way to read my codes.

[Trail X]

I had this happen to me once, but I had no codes show up. The code would be a really good clue to help diagnose. Go to any auto parts store and let it die, then have them check the code for you.

[TangoBravo]

I had this happen to me once, but I had no codes show up. The code would be a really good clue to help diagnose. Go to any auto parts store and let it die, then have them check the code for you.

I think I will go ahead and try that. The only problem is that it does not do it everytime, so it is kinda hit and miss.

[TangoBravo]

So I had the TB on in the drivway idleing with the AC on and it didn't die but it did throw the CEL and also a new one that said reduced engine power. I turned the AC off and the truck off and now only the CEL is on and it seems to run normal. Very strange problem.

[Trail X]

You need to get that code pulled.

[The Roadie]

REP usually comes when the PCM is getting conflicting data that could be unsafe. A drive-by-wire system can never be allowed to fail with WOT behavior after only one failure. So there's redundant sensors on the accel pedal AND the throttle body butterfly disk position. The sensors are compared to each other and if they don't agree, the PCM goes into limp mode and the REP light goes on. Actually, the sensors (potentiometers) are arranges so one reads back higher as it goes CW and the other one is higher for CCW shaft rotation. The pots are driven with a 5V reference and ground that comes from the PCM. A single sensor that's fed by 5V and ground, would output a full scale signal if the ground wire broke. If there was only one sensor, a single wire would result in a WOT command at any speed. That could kill people.

So there are two sensors, arranged back-to-back, so a single wire or single sensor fault won't cause a runaway vehicle.

The common item is the 5V reference voltage from the PCM, which is shared by five sensors: two on the accel pedal, two on the throttle body, and one on the fan clutch. The fan clutch harness is the most likely to get abraded and damaged, and many folks have traced REP problems to a bad harness or fan clutch internal failure.

One good experiment is to disconnect the fan clutch harness at the edge of the fan shroud and see if the frequency of problems goes down or away, as long as you're not driving in stop and go traffic much when it's hot out. Just watch your temp gauge. That will also throw a code, but you REALLY, REALLY need access to a cheap code scanner.

[angryninjaduck]

I had a similar problem about two years ago. Took a road trip to South Carolina, everything was fine at highway speeds, but whenever I applied my breaks the car would start to stutter, engine was rough, and when I came to a complete stop the car would sputter out and die. If I turned off the A/C car ran perfect.

Turns out it was a bad compressor relay. I don't recall the specific details as to why but I vaguely recall something about the compressor locking up which in turn was causing the engine to stall. But my memory is a bit dusty.

Michael

[TangoBravo]

Ok so I was able to use a friends cheap code tool and this is what came up code, p0606 and p1680 it's a cheap code machine so I have no idea what that means but that's what came up. thanks for all your hep guys, Im going to go do some research and see if I can find out what these codes are.

[djthumper]

P0606
P1680

These came from the OS but it looks like your PCM may fall under a TSB

[Trail X]

Both codes relate to the throttle control. One is a possible issue with the throttle control, one is an issue with the accelerator position sensor. I'd certainly clean your throttle body thoroughly, but it sounds like you did so recently... I'd still take a look at it. It doesn't appear to have any linkage to the AC relay... could be a coincidence, or it could be dieing due to the slightly increased load on the engine when the AC is engaged. Either way, it doesn't appear directly linked.

I'll see if I can't get a diagnostic routine for each DTC copied for you.

[TangoBravo]

Both codes relate to the throttle control. One is a possible issue with the throttle control, one is an issue with the accelerator position sensor. I'd certainly clean your throttle body thoroughly, but it sounds like you did so recently... I'd still take a look at it. It doesn't appear to have any linkage to the AC relay... could be a coincidence, or it could be dieing due to the slightly increased load on the engine when the AC is engaged. Either way, it doesn't appear directly linked.

I'll see if I can't get a diagnostic routine for each DTC copied for you.

Thanks for the help, I am going to clean everything again just to make sure we can rule it out, If you could find the diagnostic routine that would be great(no hurry it's a holiday). Thanks for the help guys.

[DirtyBacon04]

Well this same thing just happened to me today, so any chance we've come up with a cure? Ill be pulling off my throttle body tomorrow to take a peek.

[Mudwheelin]

I had this happen a few times last summer. I cleaned the throttle body and haven't had an issue since. That's what I would do if I were you.

[bdp1978]

I clean the throttle body often I would say every 60-80 running hours however since I have been using Amsoil it has never been as gunked as it used to get so I don't think that's the problem. .

Just call me curious, are you running Amsoil Fuel Additive in every tank of gas?

[TangoBravo]

No I dont.

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