HI, just got this beast running after 8 months work. The engine from a 93 Legacy started right up and idles fine. I get the check engine light and it points to the tps. I have checked all continuity to the ecm and all is good.

 I have checked the sensor and it seems ok. When I start the motor the light comes right on. Takes maybe 2 seconds and that is without touching the throttle.

  To sum up.....wires to ecm all good to tps.  Light comes on immediately after startup without touching throttle...With throttle closed the 1-2 post at the sensor is open like it should be Im lost.

Below are the testing procedures from the factory manual.  Have you run through these checks yet?

 

http://www.experiencetherave.com/subaru_manual_scans/FSM_Scans/TPS_testing1.jpg

http://www.experiencetherave.com/subaru_manual_scans/FSM_Scans/TPS_testing2.jpg

http://www.experiencetherave.com/subaru_manual_scans/FSM_Scans/TPS_testing3.jpg

 

 

The third page test/scan is the only adjustment you can do on the TPS.  Check the other tests, and then check the idle switch and adjust it if necessary.  If you still have issues and everything is within spec, then I'd check the wiring from the TPS to the ECU.

Thanks for the reply, I found some info on a site that cleared up some of my confusion. The throttle sensor tested ok when I was following the ohm readings. When I went to voltage I find I have no power coming up the red wire from B3 at the ecu....No power at pin 3 of the ecu.

 I checked this by scraping a little insulation off the red wire a few inches from the ecu. I got 0.11 volts.

 Since there is power in on the B connector I figured I cant test by unplugging the connector and going straight for the pin on the ecu.

 I checked all the power in to the ecu and all looks good.

The ECU generates 5V for that red wire.  Since you don't have 5V maybe that wire is shorted somewhere, and/or the ECU is messed up.  It's probably shorted to the braided shield around that wire; check near the ends of the wire.

 

Do you get 5V at the ECU if you unplug the TPS?

No, I tested with the tps unplugged. I put the harness together to fit the vw. Tho its possible that the wire is shorted, I don't think so as I soldered all the connectors and used shrink tube on top of that. I don't get continuity from the red to the body ground when I test at the unplugged b group at the ecu.

 Thanks

I have an EJ25 in my Vanagon; I put the ECU in the normal Westfalia spot under the bench seat.

 

Well, it does sound like the ECU is the problem then.  My diagrams don't show anything other than the ECU and the TPS on that wire for 1993 year.

 

I suppose you could build a makeshift supply for testing from a 6V lantern battery and a 1A inline fuse.  If that works with no codes and the fuse doesn't blow then the ECU is not generating the 5V power.

Well, I cut the red wire at B3 just a couple inches from the ecu. Retested with the wire off and got 5.1 volts. Now to chase the short.

Thanks for the reply, was helpful to jumpstart the brain.

Presslab.......you were absolutely right.. There was 1 single strand of shield wire that got into my heat shrink at the red power wire. Im getting too old for this.

 Thanks

B

Shielded wire can be a pain. Friend of mine cooked 3 ECUs in a Volvo 240 because of a sheilding shorted signal wire to the ignition coil. Lucky yours didnt turn out the same way.

Glad to hear its running well now!

Now I cant get the light to turn offr. I disconnected the battery for a couple hours, started the motor and the CEL came on again. Put the green connectors together and turned the key on.......light stays on, doesn't blink a code. When I connect the green test mode and the black read memory mode plugs together and follow the clear memory procedure from the FSM, I get code 22, knock sensor. Do you suppose this is an old code? Either way, I will check it out tomorrow, now that I know how these things work.

Do you get a code 22 with just the black connectors connected?

With both the black and the green connectors plugged in it will only show codes that are new. The idea is to drive the car with these plugged in, and if there are no new codes it will clear out the old ones. Any new codes will blink immediately.

 

Perhaps you have a shield problem here too as the knock sensor is a shielded wire.

With only the black connectors connected, the ECU will show stored/history codes.

 

With only the green connectors connected, the ECU will show "active" codes.

 

To clear the ECU memory/codes, you connect both the black & green connectors.

 

I've got the specific procedure for the active code check & memory clear on my site.

www.surrealmirage.com/subaru/engine.html

Ive been putting new carpet in. Thanks for the replies. It was actually the knock sensor. Checked it from the ecu like the tps. Funny, the only other wire I lengthened and managed to get a shield wire into it also. The only good thing is it didn't take long to find it.

  On the other side of the coin, I drove for the first time ion 8 months and the van ran great. No CEL, I drove till the temp guage quit rising, about 1/4 the way up.A few more little odds and ends and back on the road.

 Thanks all for the help.

 Chris