00 s80 Bad ECU?

muddblood · Post by **muddblood** » 21 Mar 2015, 21:48

Question: Is there a way to confirm rather or not the ECU is bad in my 2000 s80 t6? Here's the scenario...I picked the car up fairly cheap, but it need some work (A LOT more than I was told it needed...go figure). I pulled the codes short after I bought and I think it had 9 codes. I can't remember the exact codes, but some of them were O2 sensor codes, engine coolant temp codes, MAF code, high boost code. So I replaced the 2 upstream O2 sensors (had too, REALLY long story), and the engine coolant temp sensor and I am still getting the same codes. When I first bought the car, I know the engine cooling fan work, but then it stop. Temp gauge also reads cold at all times since the day I bought, so based on those issues, I replaced the ECT (thermostat too).

So...after A LOT of repairs, the car is actually drivable now and I pulled the codes and looks like the same 9 codes are present. I checked what little data stream I could see today and I could see no activity on any O2 sensors (upstream or downstream) and the ECT was at -40, even though it was fairly warm. It still does not run 100% right, so the MAF could actually be bad (same with the boost sensor as it falls on its face around 3k RPM's), but my main concern is the O2 sensors lack of activity...they all show no voltage or NA if I recall. O2 upstream sensors are brand new Bosch sensors from Autozone and the ECT is brand new Volvo OE purchased online (forget where). It boggles my mind to think these 3 brand new sensors are bad, so now I question the ECU.

To help further understand (or complicate) the issue, here is what I've done so far:

Used XeMODeX throttle body
New ECT
New Tstat
New t-belt, water pump, tensioner, Idler
Rebuilt both turbos
Car currently has no cat converters, straight pipes (I have them too, just waiting to get it running right to have welded in)
A few other things that will not affect the running of the car (headlight, driving light, etc)

Any help is much appreciated!

Post by **doublebug** » 22 Mar 2015, 05:48

if you have DiCE I can take a look at codes remotely.
Or post the exact list of them.

draser · Post by **draser** » 22 Mar 2015, 07:00

Apparently your ECT circuit has a problem since you're getting a low temp reading to ecu, hence the system is in open loop, hence no o2 readings. Post your freeze frames or live data as suggested. Sounds more like harness and connector issues.

muddblood · Post by **muddblood** » 23 Mar 2015, 19:23

draser - Wonderfull...Here is the list of codes:

-P0238: Turbocharger/Supercharger Boost Sensor "A" Circuit High (Powertrain, Generic)
-P0236: Turbocharger/Supercharger Boost Sensor "A" Circuit Range/Performance (Powertrain, Generic)
-P0118: Engine Coolant Temperature Sensor 1 Circuit High (Powertrain, Generic)
-P0103: Mass or Volume Air Flow "A" Circuit High (Powertrain, Generic)
-P0452: Evaporative Emission System Pressure Sensor/Switch Low (Powertrain, Generic)
-P0134: O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1) (Powertrain, Generic)
-P0154: O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 1) (Powertrain, Generic)
-P0113: Intake Air Temperature Sensor 1 Circuit High (Bank 1) (Powertrain, Generic)
-P1618: Not available in Lite (Powertrain, Acura) ( this one showed up like 5 times)

I did confirm these are the exact same codes I received before any work was done.

Oh...more info...when I bought the car, it had no cat converters (as mentioned), but when whomever cut them out, they cut out the upstream O2 sensor ports and just tied the upstream O2 sensors to the frame (yes, not even in the exhaust, explaining the O2 codes at first). At some time during my repairs, I must have not tied them up properly and they got dragged on the ground and pretty ground up. So I had O2 port welded in and then the new O2 sensors. I'm pretty sure they were bad anyway as the right turbo was definitely leaking oil and appeared quite clogged.

No freeze frame data at this point and no DiCE (doublebug). I may be able to get a freeze frame in the coming days. Also, I seem to not be getting email alerts for replies so it may take me a few days to login and check back in.

Post by **doublebug** » 24 Mar 2015, 02:05

First you need to check power and ground on all these faulty sensors.
According to the list seems that you have no signal ground. That can be the result of shortage of O2 sensors. In this case mainboard of the ECU can be damaged.
So first check and later we can discuss.

Post by **precopster** » 24 Mar 2015, 05:19

Replacing sensors is not going to get a result when all of these sensors are lacking either supply voltage or proper grounds.

You really need to get familiar with using a volt/ohm meter or find somebody who can.

muddblood · Post by **muddblood** » 24 Mar 2015, 10:23

doublebug wrote:First you need to check power and ground on all these faulty sensors.
According to the list seems that you have no signal ground. That can be the result of shortage of O2 sensors. In this case mainboard of the ECU can be damaged.
So first check and later we can discuss.

Thanks doublebug. How would I check the signal ground? Or where can I find schematics so as to know what wires to check?

Post by **doublebug** » 24 Mar 2015, 12:52

http://www.volvowiringdiagrams.com/

draser · Post by **draser** » 25 Mar 2015, 07:51

You'll need schematics and a digital multimeter as said. Then get connector pin outs on the car harness side. You'll see 2 pins for heater, and 2-4 pins for signal, one of them being ground, see schematics. Then set meter on ohms and measure ground pin to car chassis for 0 ohms. Then measure sensor heater on the sensor connector this time for a below 10 ohms I believe. Then put key in ignition and turn to 2 then set meter on volts DC and measure on sensor connector on car side the voltage for heater, should be 12 volts.

muddblood · Post by **muddblood** » 25 Mar 2015, 11:40

Excellent! Thank you doublebug and draser! I'll study the schematics throughout the week and test this weekend and report my findings back.

BTW...LOVE that Volvo schematics website!!!!