Guest 69judge Posted February 28, 2009 Share Posted February 28, 2009 I own a 90 Reatta,(3 years)it's been a great car.The check engine light is on,so I entered the code diagnosis, and it showed a code eo21 c.I did the three steps listed on 8d1-25,it showed either a bad connection or sensor.I replaced both with new parts.The diagnostics still shows the tps voltage at 4.5 volts at throttle closed.Any ideas would be helpful.Thanks...Daryl Link to comment Share on other sites More sharing options...
padgett Posted February 28, 2009 Share Posted February 28, 2009 a: sure it is 4.5v and not .45v ?b: Check it disconnected, may be a short in the wiring.c: the other possibility is a bad a/d in the ECM Link to comment Share on other sites More sharing options...
Guest 69judge Posted March 1, 2009 Share Posted March 1, 2009 Thanks Padgett,The voltage reading is 4.5 volts on the dash sreen and on my voltmeter.The one thing I noticed if I push the throttle to rev the engine up,the voltage drops,full thottle with the engine shut off the voltage drops to .5 volts.Isn't that the reverse of what it should being doing.Both the new and old TPS sensors did the same thing. What is the a/d of the ECM ?.Ive checked the ground ckt(black wire) of the TPS,but not the two(grey,Blue)The grey wire leading from the ECM shows 5.0 volts with the ign on.Thanks again...Daryl Link to comment Share on other sites More sharing options...
2seater Posted March 1, 2009 Share Posted March 1, 2009 Check to be sure it is the correct TPS. The connection is marked with symbols so check the new and old are the same. GM used two different senders that are externally identical but the ground position is different between the two. Perhaps the original was incorrect as well. I am not certain what the result would be, but it may explain the reversed operation. Link to comment Share on other sites More sharing options...
padgett Posted March 2, 2009 Share Posted March 2, 2009 You said you replaced the connector ? Any chance the wires were swapped ? Sure sounds like it. Link to comment Share on other sites More sharing options...
Guest 69judge Posted March 2, 2009 Share Posted March 2, 2009 Thanks for the help guys,I checked the TPS sensor which was correct,then I checked the harness which had the number 1 and 3 wires rev.Their colors are blue and grey,which are the same as the original harness,but in different locations on the plug. By the way it was a Borg Warner harness part.Thanks again...Daryl Link to comment Share on other sites More sharing options...
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