Service Throttle Soon Light

[TTM]

Hey guys, truck has been running like a top, no problems at all. Then in the last few days I go to start out from a light and I go to hit the gas pedal just slightly and there has been nothing there, so I back off hit it again and the truck accelerates. The problem is only when I accelerate from a stop not driving or at any speed. Today I went to go from a light hit the pedal and nothing "service throttle soon" light comes on the truck just idles in drive. The pedal went dead. I pulled over she's idleing away but no throttle. I stop put it in park shut it off start it up again and lights gone and have good throttle. Drove home no problems, shut it off and started it up no problems....
What happened? Could it be the the Accelerator Pedal Position sensor, that little box above the pedal? Any ideas?

If was turning left across two lanes of traffic and there was cars coming and this happened that would have been real bad.

[a5150nut]

First we will need some more info. What year, any mods done, FSD been changed? Have you gone over ALL ground connections? We are glad to help. maybe a little sykotic but not realy psycic..............

[TTM]

Only mods to the truck have been the installing a Sol-d 2 years ago, I checked all grounds yesterday, batteries, fuel system all good. Truck is stock. Pump replaced 2 years ago, the truck has been running fine. What I did find out was these Accelertor Pedal Postion Sensor or (throttle postition sensor) have three sensors in them, and if the PCM finds a fault in one of the sensors(low or to high voltage or circuit fault) the PCM will store a current and history DTC but will not turn on the "Service Throttle Soon" light but the truck will operate normally, but when the PCM finds there is a fault in two of the three sensors a current and history DTC will set and the PCM will turn on the " Service Engine Soon " light and at this point some performance will be lost (this is the point when I was getting poor acceleration but no light). If three of the APP sensors malfunction a current and history DTC will be stored and the "Service Throttle Soon" light will come on and the the PCM will only allow the vehical to idle. This sounds like what happened in my case. Over the past while I would hit the pedal and there would be nothing there for a second and then there would be throttle and the truck would accelerate, and all this time the PCM is storing faulty sensor codes, untill all the sensors failed. Then the "Service Throttle Soon" light came on and no throttle and all the truck would do is idle. Shutting the truck off and re-starting reset the pcm allowing it to relearn the codes and allow the truck to accelerate normally. It ran all day okay yesterday but it's relearning the faulty codes to which a time all three sensors fail again at once and there will be no throttle response. Another thing is that the PCM only stores the codes and does not show a "Service Engine Soon" light. So the only way I could of knew of a problem was the poor acceleration earlier and tested the pcm for stored codes. I priced the part out and turns out to be $ 500.00 CDN for the whole assembly, was told the you couldn't get the module seperate. Not good.

[a5150nut]

Have you pulled the codes to confirm all this?

[TTM]

Going to do that today....There might be a few of them cause each sensor may have a fault.

[TTM]

Got a DTC 27, which is a Accelerator Pedal Position (AAP) 2 Circuit Range Fault. I got this from a friend service manual. Is this right? I looks like you can test the unit to see if it's fault or if there is a bad connection/ground to the PCM. Has anybody had this problem?

[TTM]

Just a update, ordered part from Chev and got a oem pedal and throttle postion sensor. Pretty simple fix, disconected battery, unhooked the connector, took the three bolts off and install new part, cleared DTC's and all good. Throttle response way better, I never new I had that much power!!!!

These things go over time, and there will be power loss only on acceleration, but if you guys get a "Service Throttle Soon" light and a DTC with it more than likey it's the throttle postion sensor...

[twaddle]

Hi TTM,
Good luck on the Throttle position swiches, hope it cures your trouble. I haven't had that one (yet) with the old Suburban.

A while back you were having cold winter morning start problems with the Sol-D, are you still having the same trouble or did Sol-D help?

Best of luck

Jim
Biggar, Scotland (soon to be somewhere in Alberta, Canada)

[TTM]

Hey Jim, no, same ole same ole.......just keeping the truck in the shop overnight to keep the warmth in. Always keep the heat gun handy, about 3-5 mins with the heat gun resting on the intake blowing on the Sol-D and it starts right up on cold mornings (outside) ....haven't done anything different over the winter. Just have to get the Kennedy unit...mine doesn't like the Sol-D. Anything new that you heard about the Sol-D?

[twaddle]

Hi TTM,
No answers from Sol-D, although it's been a while since I contacted them, the Suburban does the same as your truck every now and then when there is a wind chill factor but no where near as low as the temperatures you get over in BC.
I just plug in the spare Stanadyne PMD that I always carry, fires right up, let it run for a minute or two then reconnect the Sol-D unit and it usually fires up.
Wouldn't buy another Sol-D, I shouldn't have to go through this carry on and it is definitely not a voltage issue.

I will probably be selling the Suburban before moving from Scotland to Alberta later this year but I would definitely buy another Suburban as it is a handy truck.
I would like to build a special with a NON electronic fuel injection system and a manual gearbox. All I would need is the time to do it.

Did you get your fault sorted out?

Jim
Biggar, Scotland

[twaddle]

TTM, check out this thread currently running, Robyn has a theory on the Sol-D.


http://www.thedieselpageforums.com/tdpforum/showthread.php?p=206509&posted=1#post206509

Good luck

Jim