Both sides of the injectors have solid test light. If the TPS was bad it would still flash a little right?
If the TPS was saying WOT all the time then the Injectors would not fire (Flash) at all while cranking.
The same as if the PIP sensor (train) was bad they would fire (Flash) then either.
If the PIP train is good
and the TPS is a good one
and the Computer has good grounds (pins 40 & 60)
and power to it (pins 1, 37 & 57)
and if the Injectors do fire while cranking then you may have a bad computer.
The above assumes the wiring and plugs are all good between the sensors, computer, solenoids and relays.
Ok thats kind of what I thought. The TPS seems to be working has .71 volts closed then goes over 3.8 at full throttle. Is it possible for the PIP sensor to be bad and still have the ignition working?
I think I answered my own question it looks like the pip signal is a seperate output to the computer can it be troubleshot with a light or meter to determine if the signal is there?
Yes the the PIP train should be 6 volts AC on a meter.
But if the Ignition is working the PIP sensor is working and you only need to look at the PIP train from the ICM to the computer.
Or if you can read the below image you test it that way.
My truck does not have an ICM just the TFI module on the distributor. So I probably need to get a wiring diagram and check for the signal at the computer then and also the test points mentioned earlier for power and ground. It's looking like its computer or wiring is there anything I might be overlooking any places where wiring in these trucks regularly shorts out or breaks?
My truck does not have an ICM just the TFI module on the distributor. So I probably need to get a wiring diagram and check for the signal at the computer then and also the test points mentioned earlier for power and ground. It's looking like its computer or wiring is there anything I might be overlooking any places where wiring in these trucks regularly shorts out or breaks?
The ICM and the TFI are the same thing.
The TFI is how the ICM is made.
TFI= Darlington output device and associated Thick Film Integrated components.
ICM= Ignition Control Module.
One other though, the Computer requires a higher voltage PIP train to work than the ICM so it is possible to have spark and the computer will not fire the injectors.
In this case you would need to change the PIP to get both to work.
Note the PIP train comes from the PIP sensor and not the TFI Module.
The PIP train just passes through the TFI Module on its way to the computer.
The TFI module does tap the PIP train as it passes through but does not change it.
That's the sensor in the distributor at the bottom looks kinda like a hall effect set up. I am assuming it gets amplified by the TFI on route to the computer perhaps both would be good to change. This truck has all original electronics except the O2, temperature, and the TFI was changed about 10 years ago.
That's the sensor in the distributor at the bottom looks kinda like a hall effect set up. I am assuming it gets amplified by the TFI on route to the computer perhaps both would be good to change. This truck has all original electronics except the O2, temperature, and the TFI was changed about 10 years ago.
No PIP train does not get amplified by the TFI on route to the computer, it just passes through it.
But the PIP train also will feed the TFI module and the TFI will use this to fire the coil if the SPOUT train is missing or if the TFI receives a START voltage. When this happens the TFI will fire the coil at base timing, 10 degrees BTDC.
Code 126 is a map sensor,the Data this sensor retrieves is used to control ignition timing and fuel delivery from the injectors..I would check this first.
I have seen that too but this is OBD 1 so am just going by the book with the reader. I dont think a missing map sensor would even cause the injectors not to run,
The MAP sensor is critical to that system.Im just saying,your having a problem with the fuel system,that sensor can be detrimental to the fuel system,you have a code for that sensor..I own a shop and have diagnosed many vehicles,when i have a code that points to a specific sensor,i check it first..Even if its wrong it could save you some time..Good Luck
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