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Discussion Starter · #1 ·
on an 89 gtc car will stumble an only hit around 3000rpm and bounce back and forth like its hitting a rev limiter no matter how much throttle you give it only code is 24 i replaced the sensor is there anything other than wiring that could cause this
 

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R.I.P Dennis Jarvis
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Code 24 - Throttle Position Sensor.

When monitored
- Ignition on
When placed in memory - If voltage above 4.7 volts or below 0.16 volts

This is from another thread. NAJ did the write up.

First you need to verify if the code 24 is a TPS Voltage Low or TPS Voltage High.
Only a scanner will give you the exact trouble code description.
You can check yourself with a DVOM.
With your digital voltmeter on a Volts scale backprobe the TPS connector signal line(OR/DB) and signal return line(BK/LB) and read the voltage with the key on/engine off and throttle closed.
Where is the voltage reading?
Is it reading extremly low(below .10 volts) or high(above 2,50 volts) with the throttle closed.
If the voltage is normal at closed throttle(.40-.90) perform a wiggle test on the wiring and connector and watch for voltage changes.
Slowly sweep the throttle and watch TPS voltage.
It should increase consistanly with throttle opening and read above 3.50 volts at WOT.
While sweeping the TPS watch for voltage fluctuations or voltage spike/dropoff.

The MAP Sensor and TPS both share the same 5 volt reference and signal return lines.
Post back with your TPS voltage readings.
 

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R.I.P Dennis Jarvis
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oops double entry
 

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Discussion Starter · #4 ·
well i have tested it with the sensor plugged in i have less than .10 key on but if you unplug it there is five volts is the sensor bad? like its shorting and losing all the voltage
 

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well i have tested it with the sensor plugged in i have less than .10 key on but if you unplug it there is five volts is the sensor bad? like its shorting and losing all the voltage
You tested it how?
You backprobed the signal and signal return line with a digital voltmeter and with key on/engine off @ closed throttle you are reading .10 volts?
 

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Discussion Starter · #6 ·
yes plugged in back probing key on engine off and i only get .086 volts on the fluke meter checking and making sure its getting contact i skinned a little bit of the wire back on the signal and the return and am testing there. If you unplug the sensor i have five volts on the signal wire once you plug it back in it looses the five volts which has got me confused as to wat the heck is goin on
 

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You probably should have backprobed the connector instead of stipping back insulation, be sure you seal those wires well when you are done.

Closed throttle voltage should be between .30-1.00.
WOT needs to be above 3.50 volts.
Slowly sweeping the throttle open you should see a constant, steady increase in voltage with no spikes or voltage drops.

If I understand correctly you are saying that with your meter connected to the signal and signal return line when you unplug the connector the voltage reads 5 volts.
There should be no voltage reading from the signal/signal return with the connector unplugged unless one of those lines is shorted to the voltage reference line.

Unplug the connector and with the key on probe each of the 3 terminals with your + probe while the - is connected to an external ground.
What are your voltage readings?

VT/WT(5 Volt Reference)
OR/DB (Signal Line)
BK/LB (Signal Return)
 

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Discussion Starter · #8 ·
I am checking the five volt reference using an external ground but when the sensor is plugged in im using the signal and return one lead on signal one lead return and am getting less than .10. I also checked the five volt reference"signal" plugged in one lead to battery ground on lead on signal wire and have less than .10 how can that be happening why does my five volts go away
 

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I am checking the five volt reference using an external ground but when the sensor is plugged in im using the signal and return one lead on signal one lead return and am getting less than .10. I also checked the five volt reference"signal" plugged in one lead to battery ground on lead on signal wire and have less than .10 how can that be happening why does my five volts go away
There are 2 reasons for a Code 24 to set and two code descriptions...
Voltage high(open circuit) or voltage low(shorted circuit)
If I understand correctly your voltage readings are...
.10 volts with TPS connected and voltmeter connected to OR/DB and BK/LB
5.00 volts on VT/WT with TPS disconnected and .10 volts on VT/WT with TPS connected.
This would indicate TPS Voltage Low.
You are losing your 5 volt reference because it found an alternate path to ground when connected to the TPS or the TPS is shorted.

You have to disconnect the TPS and SMEC and use your digital ohm meter to check the v-ref, signal, signal return to see if they are shorted to each other or to ground.





 
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