Weird intermittent CTS problem - solved

[DaveT]

The last couple of drives in my 1987 wagon, the engine was idling at 3000RPM.  So today, I started troubleshooting the CTS.
CTS measures ok.  The wire from the ECU to the CTS is good.  Ohms to GND is not right.  GND to CTS wire is good.   Pluged in another tested good CTS, still get weird ohm reading from the ECU signal wire to GND, like the sensor is open.  Moved the car between some of this, and now the ECU is giving me the code 21 for the CTS.    So the wires check good, the sensors check good...  WTF? 

This 1987 was wired with a round connector for the CTS.  All of the other [newer] EA82 SPFI powered cars I've had used a smaller oval shaped connector.  The original CTS must have failed a log time back, and when I replaced it, I made an adapter to convert the round to oval, so I didn't modify the harness or the sensor.   And I made the adapter from some oval connector that was keyed with the tab lock on the other side, and modified it so it would mate with the normal CTS connector.  Except I did not notice that the connector would now go together in either position, which doesn't matter electronically, but it turns out the pins were just resting on the sides of the sockets on the mating half.  When I turned it around, they mate properly.  Oops!  But how long it has run with the flaky connection, is rather surprising.   It's not like I was having trouble with it for years. 

[Dee2]

Intermittent problems can be a nightmare.  Finding something as vague as turning a plug connector around is nothing short of amazing.....

Hope that solves it permanently....

[Step-a-toe]

Top marks for:

finding it

sharing

and letting on it was your work

(Usually some unnamed slack bum you can't smack about for it)