1995 850 ECU's (2?) and OnBoard DTCs

JeffCarpenter · Post by **JeffCarpenter** » 09 Feb 2014, 20:17

I would be very interested in opinions regarding the following situation...
I am a little puzzled about a couple of things on the 1995 850 that I purchased (From a small Volvo shop, it was one of their service loaners).
Firstly, when trying to add the car to my IPD shopping "Garage" they ask me about which Fuel Control system my car had. From what I've heard, and what I think the attached (Trying to attach) PDF is telling me, I should be able to look in the large square box behind the 2 little on-board diagnostic boxes (We'll get to them momentarily) and I think I am supposed to see 3 ECUs...Starting from the passenger side...Transmission ECU, Fuel ECU, and Ignition ECU. However, when I look in my box, I only see 2 ECUs, (I will try to attach a picture of these) neither with labels that indicate anything to me. Is it possible that I was sold the car without the Ignition ECU and it still be able to start?

Secondly, regarding the On Board DTC (2 little on-board diagnostic boxes)...
I don't have receiving connectors/plugs inside the little boxes for positions A-5 (which is skipped on numerous list but referenced as a Trans Control position on others)...
I also don't have receiving connector/plug for positions B-3 & B-7, also not on a number of the list.
When doing the test with the jumper line on the DTC boxes, I am getting absolutely no response signal from positions A-6, B-1, or B-6.

Yesterday I did the test on each position that I could get a reading, then cleared the codes, and read them again today. (NOT a lot of driving between)
Here is what my codes were the first day followed by the second day for each code...
A-1, Both days received 1-2-4 (Mode selector faulty or short circuit to ground, the switch inside the car on the console was broken when I got the car and I changed it out for an "Unproven" one)
A-2, First day received 2-3-3 (Long term idle air trim) but the next day I got the clean 1-1-1
A-3, First day received 4-4-4 (No power supply to valves in hydraulic unit) but the next day I got the clean 1-1-1
A-7, First day received 1-2-2 (Temp. sensor interval too long) but the next day I got the clean 1-1-1.. On the first day this same position have also pulled a 1-1-3 (Fuel gauge open circuit) but again the next day A-7 got the clean 1-1-1.
B-5, 1-2-7 (SRS) but the next day I got the clean 1-1-1.

Thank you in advance for your time & thoughts,

Jeff Carpenter

JeffCarpenter · Post by **JeffCarpenter** » 09 Feb 2014, 20:27

I also still don't know which Fuel Control system I have.
I looked at where the (A-7) Temp Sensor is and it looks green and corroded. I'm thinking that code may come back and I should replace that with the Thermostat.
I'm getting hard shifting at times (Replaced the Trans Torque mount already)
I do know that one of the hydraulic "bubble" motor mounts is leaking. Not sure of the other.
Throttle Body, air Filter, and MAF are clean. New Timing Belt, Front Seals, and Water Pump.

Post by **erikv11** » 09 Feb 2014, 22:40

Your car has the Motronic 4.3 fuel system.

When there are 3 ECU's the car has the Jetronic system, when there are two ECU's it is Motronic. Which is a good thing.

I'm not very good with the diagnostics box, better leave that to someone else.

JeffCarpenter · Post by **JeffCarpenter** » 11 Feb 2014, 09:04

Thank you regarding the Motronic 4.3 determination...So just for my own education, what are each of my 2 ECU's? Is one of them combined/dual duty? Is the Motronic control somewhere else?

Jeff

Klausc · Post by **Klausc** » 11 Feb 2014, 09:48

You have an automatic tranny and no turbo. One of the CPUs is for the tranny and the other for Motronic, which includes the ignition.

B-1 is for ECC, electronic climate control, which you do not have.
B-6 is for power seats, which you do not have.
B-3&7 are not used.
A-5 is for the turbo control unit, which you do not have.
B-2 is for cruise control, and if you have it, you cannot clear 1-2-2.

The codes that you cleared were probably pending, check engine light not on. I used to go through all of the nodes at each oil change, just to clear some garbage pending codes and to keep abreast of the mechanical problems that might need investigation later.

The gear selector switch error could be the switch. With the engine off, push all three buttons and make sure they stay down and pop up with authority. My switch tended to go all the way down and then slowly 'float' up.

Have you flushed the ATF yet? Check the color, it should be pink/red.

The hydraulic motor mounts are the most difficult to replace.

JeffCarpenter · Post by **JeffCarpenter** » 11 Feb 2014, 11:24

Thank you!

Vehicle service history that I got with the car says…
Plugs replaced 3 months ago (4,000 miles ago)
Last Trans Flush was 2 years ago (14,000 miles ago)…5 months earlier they had flushed the trans also with a service note of “Possible a PNP Switch and/or Throttle Position Switch” but there is no record that they ever installed either of these. How would I know if I need either of these?....__________
Thermostat was 2 years ago (14,000 miles ago)…One of the codes I had that cleared (Could come back) was the A-7 Temp Sensor, ETC…It looks old and there is no record of replacement.
Spark Plug Wires 2 years ago (14,000 miles ago)
Front O2 Sensor 2 years ago (14,000 miles ago) *THERE WAS A NOTE THAT THE REAR MIGHT NEED REPLACED, BUT THERE IS NO NOTATION OF THAT BEING DONE. WHAT ARE THE SYMPTOMS IF THAT IS NEEDED?.......______________________
Serpentine Belt 2+ years ago (14,000 miles ago)
Evap Valve & Filter 2+ years ago (14,000 miles ago)
How hard are the hydraulic motor mounts to replace? I have watched the attached video and this guy makes it look like it’s not too terrible…
I very much appreciate all comments/input.
Jeff

JeffCarpenter · Post by **JeffCarpenter** » 11 Feb 2014, 11:33

Actually there is a note for the replacement of the "Gear Position Sensor"...Is that a "PNP"?

Klausc · Post by **Klausc** » 11 Feb 2014, 11:48

Gear postion sensor is the same as the park/neutral position switch.

Wait for warmer weather for replacing the donut mount. It's not that easy!

Replace the ECT sensor. If the thermostat was OE, then it will still be fine.

Good plug wires will have date of manufacture on them. The spark plugs should be 3 prong.

When the front O2 sensor starts to go bad, you will first notice a decline in MPG, followed by an error message that the rear O2 exceeded limits. The O2 sensors are usually good for 100-120K miles.

JeffCarpenter · Post by **JeffCarpenter** » 15 Feb 2014, 08:44

So I ordered the Temp Sensor, ETC from IPD, with a few other things, including a new thermostat (Just wanted to be "All good" there) and am awaiting the delivery. I noticed that the thermostat does not come with any fiber/paper gasket but just an "O-Ring" type of seal. Is this all it needs? Should I add Perma-tex to the seal or the matching surfaces? Also, I've heard that wrenching/space on the Temp Sensor, ETC is a bit tight, what is the best tool for that install?

JeffCarpenter · Post by **JeffCarpenter** » 15 Feb 2014, 08:54

I also went looking for info to confirm the Fuel Managment System.
Attached is a photo of the label on the side of the ECU that is middle postition in the box, but as there are only 2 units, this is the closest unit to the motor. The label is Bosch, with the numbers 0 261 203 165

The second attached photo is the TCI ignition coil, on the driver's side upper fender. Again, the label is Bosch, with the
numbers 3 507 934

Can you help me know for sure what my Fuel Management System is (I've heard Motronic and LH3.2 per some Volvo info linked to the Vin) and/or any other info in light of the other things we talked about?

Thank you again for your help,

Jeff Carpenter