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Wiring diagnosis question

jon_allen

Regular Contributor
Hi Guys

I could use some help regarding a low TPS output signal.

The output V is less than 1.2v at WOT.

With the harness disconnected at the TPS the ref. V is 5 v which is good.

With harness disconnected and the ignition off I have 1.2 ohms at the TPS ground wire on the harness side which is good.

However, with the ignition turned on I have 25 ohms resistance at the same wire, which would be present when the motor is running likely causing an issue.

How can this be?

Thanks in advance

Jon Allen
 
To properly test the tps you need a analog ohm meter. From the input terminal check resistance to the other two. The needle shoulf make a nice smooth sweep from low to high on one and from high to low on the other. If the needle on the ohm meter skips the tps is bad. Have you cleaned all of the connectors with electrical cleaner and put back together with dielectric grease? Sand all grounds metal to metal? Look for any burnt, cracked or broken wires and fix as necessary. A thorough inspection and cleaning of the wiring system is allways the first step. If all the electrical components check out then the computer is likely the issue.
 
if you give a bit more info on how you are doing the measurements cited - which meter and where the lead go - it can only help....

I'd suspect the 'increase' you see is due to the ignition switching on which can induce a bias on the meter.....

Many times, you are better off measure resistance on isolated circuits and measure voltage drops (or differentials) on powered circuits...
 
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