94 960 ECT sensor

zaneallen · Post by **zaneallen** » 10 Dec 2017, 09:48

I have a 1994 960 with 251,000 miles. For a 17-year-old, I would say I care way too much about it. I recently swapped the head gasket due to an external leak, and actually enjoyed doing it because it was straightforward with little frustration. However, what is frustrating is the ECT sensor issue I have been having. Recently, the CEL came on during a cold start with the ECT code, so i bought a new one, swapped it out, and the code keeps coming back after a reset. So I figured that maybe the connecters were just being pushed back in their housings due to volvo’s crumbling connector insulation; but I removed the housing and could see that the pins were, in fact, connected. It idles very rough after prolonged city driving and bucks in 4th gear when you give it just enough gas to not downshift. I don’t believe it’s a wiring issue considering I replaced the entire harness when I did the head gasket. There also doesn’t appear to be corrosion on the connectors. Any help or input is appreciated.

Post by **RickHaleParker** » 10 Dec 2017, 12:34

The ECT is connected across pins 20 & pin 30 of the ECM. Pull the ECM and check the connection there. Sometimes just pulling and reinserting the ECM will make a problem go away for good. Best to do so with the battery disconnected.

Post by **jimmy57** » 10 Dec 2017, 13:38

ECT for ECM is on the back of the head for that year model, not the one by thermostat. 1996 is the year they used one by thermostat. Also the insulation crumbles on the connectors on harness side plug for one on back of head. That could let the connectors slip back and not connect well.

zaneallen · Post by **zaneallen** » 10 Dec 2017, 15:50

yes i replaced both the rear one, and the one that screws directly into the radiator hose. i will try to disconnect the ECM.

Post by **RickHaleParker** » 10 Dec 2017, 16:03

Keep in mind, a thin layer of oxidation is enough to cause problems. Never hurts to clean them with electrical contact cleaner.

zaneallen · Post by **zaneallen** » 10 Dec 2017, 18:55

disconnecting the ECM didn’t help unfortunately. still idles very poorly and acts like it’s not getting fuel after the torque converter locks in every gear. CEL hasn’t come back yet either

Post by **RickHaleParker** » 10 Dec 2017, 20:40

If the ECT code does not come back, disconnecting and reinserting the ECM did what I hoped it would do.

Any diagnostics codes from the Transmission Control Module? Have your ran test modes 1-4? (selector cable in hole #1)

If you don't already have it ... 1994 Volvo 960 Transmission Diagnostics: http://caunter.ca/volvo960/ce14807.pdf

zaneallen · Post by **zaneallen** » 01 Jan 2018, 15:03

My CEL was solved after replacing the rear ECT sensor. my idling and rough running issues was a coil that had insulator residue blocking the connection from being complete

Post by **RickHaleParker** » 02 Jan 2018, 14:06

Good to see you fond the problem.