I changed my FIPL/TPS on my '92 7.3 IDI which ran for a month like a dream. Then out of nowhere, a month later, had it shifting ******* second and O/D. Bogged out with O/D at 40 mph. Checked my voltage and I was running at 1.6V and idle and up to 7.2 at WOT What happened there? Anyone know?
7.3 idi throttle position sensor question
- Thread starter zmck150
- Start date
HS108
Diesel Newb
Could have loosened up, next time maybe put a little blue loctite on it, or switch out the bolts so you can get more torque on them vs the torx screws
I’d reset it and see how it works out from there.
I’d reset it and see how it works out from there.
ifrythings
Full Access Member
Are you 100% sure you got 7.2v WOT? The tps is only fed 5v from the TECA/TCM, if your getting 7.2v then the 5v vref is way out of spec and could be a bad TECA/TCM, also the BARO sensor is probably bad also as it runs off the same 5v vref as the tps sensor does
XOLATEM
Full Access Member
@ifrythings knows what he is talking about...something is wwrrooooonngg with the electicals...the only thing that I would chime in with is to get a good DVOM and check what each wire to the sensor is doing with KOEO both unplugged from the sensor and then plugged in and back probing.
Then you can get to the bottom of what the sensor is seeing and sending.
Ifryman is also right on about checking other sensors in the circuit because they all share the 5VDC reference voltage and the sensors and connections can fudge the volts for all of them.
Maybe @franklin2 can round us up a wiring diagram for the circuitry so we all can see the relations between them all..?
One other thing...how are all of your grounds..?
Just my .02
Then you can get to the bottom of what the sensor is seeing and sending.
Ifryman is also right on about checking other sensors in the circuit because they all share the 5VDC reference voltage and the sensors and connections can fudge the volts for all of them.
Maybe @franklin2 can round us up a wiring diagram for the circuitry so we all can see the relations between them all..?
One other thing...how are all of your grounds..?
Just my .02
MtnHaul
Full Access Member
Not positive how to reset it? I disconnected the wiring harness, tried to adjust it again, but nothing seemed to work. Any actions that require something different? Much appreciated.
ifrythings
Full Access Member
Before you can fix anything you need to double check the vref voltage going to the sensor and make sure its right, if it’s truly 7.2v you need to figure out why (most likely bad TECA/TCM) it’s so high, you can throw as many TPS sensors at it, adjust it till you throw the thing across the yard, you won’t get it to work if the vref voltage is screwed.
Put your meter across both outside wires on the TPS, do NOT use the battery or any other place for a ground, if you get 5v or lower then your TECA/TCM could have a ground issue, if you get 7.2v then check the power and ground going to the TECA/TCM, if that is good then I’d start looking for a new TECA/TCM module.
Gotcha. Yeah all the info I've read kept saying to use negative terminals on batt. I will try my outside wires on the sensor and also check the power and ground going into the TCM. My colors are t the same as the schematics so is my neg volt terminal on top or bottom wire for the TPS. Also, how to exactly check the voltage on my TCM? Haven't messed around with chasing wires much yet so still need some help with that. Much appreciated as always.
ifrythings
Full Access Member
The reason I say don’t use the battery is because we don’t know if the ground to the TCM is good, if it’s bad and the TCM is “floating” then any measurements will be off, measure right at the sensor using it’s dedicated ground back to the TCM will help rule out odd readings. Grey/red is the ground and brown/white is the 5v vref, measure that and let’s see what you get, you can measure it either at the TPS sensor or barometric sensor about the heater box.
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MtnHaul
Full Access Member
A cheap-o OBD1 code reader can be helpful here as well.
Alright that sounds like a detailed explanation there. I appreciate that info and will definitely be measuring that way from now on. I'll let you know what I end up reading when I get to it. Thanks again
