Truck is showing no codes ( It did show a 19 and a 26 with CPS disconnect, with the CPS connected no codes) Truck will Intermittently ( a lot) go to idle and the Service engine service and Service throttle soon lights come on, after less than 30 seconds the lights go out and the trunk is normal, From reading my manual the service throttle soon light comes on and the truck goes to idle should only happen when all 3 TPS's fail. I have moved the tps wires, checked grounds trying to make it happen with no luck. Is my TPS bad? It seems like all 3 fail at the same time. Maybe there is some thing else that causes this? Not sure. thanks for the help. Joe Edited by: joefenderman

Sounds like its either got to be that or a wiring problem, got a friend who will let you borrow one to try in yours?

No wish I did. Do these fail very often? Woundering why it has 3 tps. It seems that the computer sees them fail at the same time. Not 2 bad and 1 intermittent. Are The pots lined up with one shaft? how much are they? this is what my GM dealer called a IP problem. Glad I decide to chage it myself. New IP pump can't hurt. But I need my truck. What is the reliability of these trucks? mines 94 hd2500. I do like the truck thes feel of the diesel and the over all ride. But after reading these post I worry about intermittent stallings. I have a friend who has a 6.2 he got 220,000 miles on with little problem, rebuilt and still going. Thats why I went with 6.5l . Anyway thanks for all the help.

200,000 Miles plus is not unheard of for a DB2 pump, its certainly not the norm, at 100,000 most will need to be rebuilt, but I've seen one that somehow made 300,000 but it ran pretty poorly for a lot of that. DS Pumps will never touch that for one, once anything internally gets worn to the point that it won't function properly you get a code or a failure, and DS pumps have a lot more parts not to mention electronics. DBs pretty much just go until something breaks or gets completely worn out inside. I would say that a DS pump that is carefully maintained, should be able to go a minimum of 40k but I would never expect one to make much over a 100k.

WOW just called on the Tps unit. $410 you have to buy the whole assy . looking for a used one if anyone has one

yikes, so I guess your not gonna go buy it just to try it then...


wrecking yard maybe?

It looks like the throttle pedal is the problem. App1 has 1.5v Bad, APP 2 has 4.5v Good ,APP 3 has 3.5v bad. When the truck goes to Idle. If I understand this all 3 should have 4.5 volts at idle. Wish truck would have given code 26 before I change pump. The first problem was I thought truck was stalling with both lights coming on and truck losing power It wasn't until I drove the truck more with the new IP That I realized It was only going to idle. Maybe this will someone else who is seeing no codes. Givr the computer a hard fault .Disconnect the temp sen when the service engine light comes on pull the code maybe it will show the soft failure along with the hard failure. I'll keep you posted when I find 1. Edited by: joefenderman

Well installed used Throttle pedal . still same problem. Does any one know what else can trigger the service throttle soon light? Maybe my computer is bad ? The manual does not tell you how to debug the TPS very well. that I can see. Any Idea's? I don't know were to go from here I hate to take it back to the dealer he had it wrong with the IP. Thanks For any help Joe


Nope new computer didn't help.


Edited by: joefenderman

Bad connection somewhere.

I 'm looking and hoping. The voltages look good on the TPS now but same problem. I'm not sure if anything else can set the service throttle soon light. I was hoping someone would know I've been reading some post were the light has been triggered for some other reason. Tomorrow I was going to jumper a hot wire to the fuel pump , and if nothing there I'm going to hook up a fuel guage and see if i loose pressure. after that I'll get a oscope from work and watch the lines going to the TPS and the IP to look for problems. after that I shoot the truck.http://www.dieselplace.com/forum/smileys/Confused.gif. Thanks for the response Edited by: joefenderman

TDG, isn't the fuel driver part of the throttle?

You don't have any codes?


The wire to the map sensor got shorted to ground on mine today and gave me 2 or 3 codes for the APP (gas pedal)


I am guessing that it was just draining the voltage to the computer way down which put them out of range.


I didn't try driving it while it had the problem so I don't know if it went to idle only.

I don't have any codes after I changed my pedal I think of three of the TPS units were bad giving me the code 26, But I still go to idle and both the throttle and service engine light come on than go off and every thing is fine. It's not happening as often now. I have to drive it for maybe 20 Min's for it to happen before it was all the time. I think thats because I'm trying to fix it. Things never happen when you want to fix them ;). I'm headed out with hot wire on the fuel pump to see if that helps


No help , New lift pump no help?http://www.dieselplace.com/forum/smileys/Cry.gifEdited by: joefenderman

Scantool could help you "see" what the truck is doing.
It's alot better at telling you DTC's especially momentarry ones.
Having a look at sensor readings while it goes to idle should help you pinpoint it.

I have been driving around with a scope on pmd fuel solenoid and closure lines. The closure signal go's away or to 0 volts when it dies and both fuel solenoid signals go to 0 volts. I drove around for a hour to watch both fuel solenoid line signals coming from the computer to the PMD. turck didn't fail again. I'll have try again tomorrow. Not sure why there is 2 lines. If any one knows or something else I can look at. would be great thanks Joe


I'm looking at another wire diagram shows both fuel solenoids lines tied together and one that show them as different connections. what gives?





Edited by: joefenderman