Ok so my pressure sensor in my 87 T2 is acting up. Gauge doesn't go to 0 on ign on, and my Rtek reads 1-3 Psi all the time. I tested mine and it doesn't read the right voltage at 5(?) in of HG so i figure its dead. I dug out my spare and same thing. I got one from Ebay. and put it in today. The gauge went to 0 on IGN, but of course the car wouldn;t start. Flooded with a low batt, so I killed that batt trying to start it. I charged the bat for a few, tested it again and still no dice. ( I have a really screwed up hotstart, don't ask,plus it wasn't hot )While recharging I thought" well it ran 3 days ago so maybe its the new sensor". I put the 2nd one back in and the gauge read 0 at ign so it must be fine after all. But i had to go to work and took the vert (beautiful day here anyway). When I got home the batt was all charged, and I was ready to try again. This time both sensors #2 and the newest one, showed full vac at ign, not good, but i got the car started.

Long *** story sorry.

Anyway, I kinda doubt that both are dead(all three actually) since they changed from working to not.

So Is there a way to test these things OFF of the car. I wanna make sure that a short isn't killing the thing even if I put in a brand new one. Not going to happen at $400 bucks but the principle is sound.

There has to be a way to a voltmeter to two of the connectors and see how the settings change with a vacuum/pressure change.

My other thought is the connector/wires. I'm going to clean out the connector tommorow if I can find my circut cleaner. and I've been checking the wiring diagram in my FSM but damn that thing is weird! It appears that the wireing goes through the pressure sensor and the TPS and the ATP.

Any help much appreciated.

Well, its gotta be electric. It worked fine this afternoon, and now its reading dead again. I got some contact cleaner for the conectors and I'll see if that helps. IF not its got to be in the wire harness.

I would still like to know how to test the sensor off of the car though.

 

It sounds like an intermitent. After cleaning the connections (make sure to clean them prior to using contact jelly/dielectric grease) if you're still having problems trace the wires through making sure there is no fusion open wires grounding out rubbing against something that produces a high magnetic field (like improperly shielded spark plug wires).

 

You can test the sensor out of the car if you have a power supply, voltmeter and vacuum pump (or you can suck).

Get the FSM and look up the connections to the sensor. It's a 5V supply as I recall. Connect up power and ground, the connect a voltmeter to the output. Apply vacuum and pressure to the sensor and watch the output of the voltmeter. Not sure off hand if the FSM contains values, but you will be verifying that the sensor is providing an output even if you don't know if that output is correct. You can also compare with a known good unit (in another car).

 

Well, I didn't need to result to out of car testing. When it decided to work, i tested all three sensors I have and they all tested fine! I cleaned the connector with a cleaner and it is still intermitent. Im not driving the car at all, just starting it and testing it. Warming up and such. I'm going to give the connectors a better cleaning, and use some dielectric grease in it. (Damn radio shack doesn;'t sell it!) My guess is its in the wires someplace. I'm going to have to study and see wich wires go where and do some continuity testing. This will be a pain...

Thanks for the help, any more ideas let me know.