Hey Guys, what's the easiest way to check the tps voltages (on the car)?

Larry

 

With a voltmeter!

 

Larry,

Download the Haynes for specifics, but the reading for a closed throttle is between 0.2 and 0.5 Volts, wide open is 4.8v. The Haynes has diagrams to demonstrate which wires to probe for the reading, dependent on the MY.

If you're looking for the easy way.....sorry. Got to have the TPS connected to get the readings, but you may be able to do it with the throttle body off (that isn't easy either is it?) the manifold in order to properly fasten the TPS in place once you've got the range correct. The engine does not need to be running, just the ignition in the "on" position to read the circuit.

 

Look for the Jaguar Publication S91_AJ6 4.0 Engine Management I uploaded in the large file area. It will have all the info for Fuel Fail 17.

bob gauff

 

Thanks guys, was just looking for best tips for inserting the probes, don't have any radical problems, just wanted to see what readings I got ...

Larry

 

Hi Larry,

On our '93 (and probably on your '94), the TPS electrical connector is sealed so it can't be back-probed in the standard way. I used a couple of pieces of small-guage solid copper wire to insert into one pair of female connector terminals at a time, then partially reconnected the two connector halves so the terminals were in contact but the connector wasn't wedged too firmly on the two additional wires. With that setup I could easily manipulate the throttle cam and measure the voltages at each end of its range of motion. The TPS in the '93/'94 cars has two different resistance tracks, one that feeds the ECM and one for the TCM, so you have to measure them separately. As I recall, there are six wires on the TPS, but only 4 are used, and you may find that the voltages for the ECM and TCM tracks are opposite one another - when one is high, the other is low, but I may be wrong about that.

While you're testing, move the throttle cam as slowly as you can and watch for any dead spots on your meter. The resistance changes so quickly it's hard to do, but worthwhile.

Have you drilled drain holes in your TPS case and flushed it with zero-residue electric contact cleaner spray?

If you want to compare your readings, somewhere in the Jag-Lovers archives I posted the voltage readings for the TPS in our '93.

Cheers,

Don

 

Hey thanks Bob, downloaded your .pdf a long time ago, an invaluable resource for sure. My car never threw a FF17, the only FF I ever got was a very annoying and long recurrent FF23 which I managed to get rid and hasn't reappeared in about 6 months ... but - the car is still running on the rich side, no doubt the the ECU is compensating within the 10% tolerance as the FF hasn't reappeared.
Reading through the FF23 flowchart in the .pdf last night, I just noticed something I hadn't done ..the chart says to disconnect the yellow and blue connectors at the ECU and re-plug them - I'm assuming this performs some sort of reset?

cheers

Larry

 

Thanks Don, just the run through I needed. Sounds like a plan!

No holes in the tps as yet, idle is pretty stable and acceleration smooth and shifts seem fine too ..so I'm following the "if it ain't broke" path on that issue for now !

Larry