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68c10airstream · 03-11-2018, 12:59 PM

After doing driveability work for years my rule of thumb is this; i like to check circuits live with a voltmeter. Checking circuits for continuity is a great follow up after you have done the live voltage checks. Doing live checks is great because it's under load.

I'll use this as an example that usually helps; take a garden hose, full of water, nozzle on the end so water is not leaking out. Imagine taking a needle and poking into the hose in various places. Water and pressure are present. The nozzle when opened just didn't blast out of it like it used to. You did the static (at rest) (continuity) tests and checked fine. Pressure and water were present. What you didn't know was the hose was pinched almost closed. Now you test it in use and the upstream pressure is good, but the downstream pressure dropped off a lot. Problem is in between these two points. You never will find it at rest, but in use it's obvious. You can now relate this to checking a circuit in use. You poke an upstream circuit, it's good. downstream voltage check is low voltage and the trouble is between these two points.

I suspect what you have is poor connections at the tps. I'm not a programmer so your story above is worth considering looking further into. Work with what you have in front of you. If you still have your old tps, carefully cut it apart and save the metal terminal(s) and do what i call a connector drag test. Take the tps connector and slide it over back and forth on the connector in the harness. You should be feeling a slight drag. If not, you will need to replace/repair as needed.

With the vehicle running, pull the backside of the tps plug in harness back by sliding the weather pack rubber back to expose the metal connectors. 5.0 volts has to be there before you can go any further. If not, other items driven off of the 5 volt supply are dragging it down, been there, done that before. You would also need to check at the pcm for the 5 volt supply to be coming from the pcm.

During my jeep days, from memory i had a bad map sensor drag the 5 volt supply down, but the tps was the circuit with the fault with no voltage. Disconnected the map, 5 volts was now avaliable at the tps. Seemed weird because map should be more important than tps in a speed density fuel injected system.

03-11-2018, 12:59 PM	#7
68c10airstream Registered User Join Date: Mar 2013 Location: Marquette michigan Posts: 828	Re: TPS issue and troubleshooting help After doing driveability work for years my rule of thumb is this; i like to check circuits live with a voltmeter. Checking circuits for continuity is a great follow up after you have done the live voltage checks. Doing live checks is great because it's under load. I'll use this as an example that usually helps; take a garden hose, full of water, nozzle on the end so water is not leaking out. Imagine taking a needle and poking into the hose in various places. Water and pressure are present. The nozzle when opened just didn't blast out of it like it used to. You did the static (at rest) (continuity) tests and checked fine. Pressure and water were present. What you didn't know was the hose was pinched almost closed. Now you test it in use and the upstream pressure is good, but the downstream pressure dropped off a lot. Problem is in between these two points. You never will find it at rest, but in use it's obvious. You can now relate this to checking a circuit in use. You poke an upstream circuit, it's good. downstream voltage check is low voltage and the trouble is between these two points. I suspect what you have is poor connections at the tps. I'm not a programmer so your story above is worth considering looking further into. Work with what you have in front of you. If you still have your old tps, carefully cut it apart and save the metal terminal(s) and do what i call a connector drag test. Take the tps connector and slide it over back and forth on the connector in the harness. You should be feeling a slight drag. If not, you will need to replace/repair as needed. With the vehicle running, pull the backside of the tps plug in harness back by sliding the weather pack rubber back to expose the metal connectors. 5.0 volts has to be there before you can go any further. If not, other items driven off of the 5 volt supply are dragging it down, been there, done that before. You would also need to check at the pcm for the 5 volt supply to be coming from the pcm. During my jeep days, from memory i had a bad map sensor drag the 5 volt supply down, but the tps was the circuit with the fault with no voltage. Disconnected the map, 5 volts was now avaliable at the tps. Seemed weird because map should be more important than tps in a speed density fuel injected system.