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1997 just idles

1K views 5 replies 3 participants last post by  Tiger02 
#1 ·
Looking at this wiring diagram that I found on this site does the wire from the tps (which I thinks stands for throttle postion sensor) go to the fuel pump relay? I have changed a few thing since the truck went into this mode. Pcm and the sensor for the oil above the head and also the sensor on the foot pedal but nothing helps. I have current coming to the tps so now with changing the things I have I am wondering if there is a wire broke from harness at the tps to the fuel pump relay. How would I check if the relay is bad. any help would be greating appreciated. The check engine light is on and if I someone to put a code reader on it I will have to have it towed to a shop, so I was wondering if I could just get lucky and someone could help me with this problem. I would hate to take it into a shop if its something I could fix myself.
Thanks
 
#2 ·
The tps (throttle position sensor) has another switch just below it called the ivs (idle validation switch) they must be in sync or it will just throw a code and check engine light and idle all day.

If you have a multimeter you can check the resistance across 2 of the 4 wires. At idle should be somewhere around .69 ohm at wot (wide open throttle) should be 4-4.3 when you let off the pedal you should hear the ivs click. And it should close the circuit I believe. If not then it needs to be adjusted. You can bend the tab that pushes it ever so slightly. Some people drill and tap and adjusting screw into it.

If the tps changes in resistance too much without releasing the ivs it will throw the light. First unplug the ivs and make sure it opens and closes when you push it. I'll see if I can find a link to a write up.

When I got my truck it had nearly half pedal travel with nothing then it would take off like you floored it. First time I adjusted those 2 sensors it have me a check engine light the first time I pushed the pedal down. A couple little tweaks and it works great now. Best of luck chief


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#3 ·
Any quick lesson on how to use the muiltimeter? The IVS seem to work since there is current going in and out or not out depending if your foot is on the pedal. So I wouldn't think the IVS right? I bought a new tps but no luck. I know there is current coming in with a 12 volt light (dim) but no mater how far I press on the pedal there is no current coming out of either the other two wires. My has 3 wires to it's harness not 4 so I don't know if it's different years me and you are talking about. Any thing you can tell me would be appreciated.
 
#4 ·
A year light isn't really going to help you out much here. A multimeter set to read voltage is going to tell you exactly what you need to know. One wire is a ground. Another is a 5v reference and the last is the output voltage of the throttle position sensor. If I remember right they want tps voltage somewhere around .68v to .70v with the pedal released at idle position. The ivs switch should open within .2v (i think)or it will set a check engine light and not come off idle. On the tps there's a little wiggle room in the 2 screws to "clock" the sensor. Try a quick Google search for obs accelerator pedal fix. There's a great write-up out there that gives you exactly what you need and then some. Its a pdf and from another forum but the guy absolutely nailed it.

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#6 ·
Had the exact same problem a month ago or so. It would idle only, but after a few minutes I was able to drive it. Ended up just being the IVS switch sticking in the idle position. I pulled the pedal assembly off, which only take a couple of minutes, stuck it in a vice and played with the tab to get it bent just right. The write up that Edwester03 refers to was a big help. Much easier throttle on the low end now as well.
 
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