Senile 850?

[T5hug]

Ok so i knew the old girl was getting on a bit but after getting an ABS light (which went back out) i checked the codes and got a 3-2-5 "memory failure"!

Only had the car back on the road for a few weeks. I had checked the codes before MOT and got the 1-1-1 but after only 800 miles she has lost her mind! To be fair after 2 weeks camping with my wife i almost did too!

Shes still running sweet and the ABS light is back off. Should i worry?

Also should i get this looked at i dont want to leave post it notes everywhere for her!

[NorthlandDave]

How long have you had the car off the road? If you've had the battery disconnected/gone flat you can get this code. I think the 'memory failure' just refers to it forgetting the adaptive values which would store themselves again after a drive. The code shouldn't be much to worry about though.

Sometimes the ABS has to run diagnostics after which it turns the light out, which sometimes requires driving the car over 12mph, so might have just been that. If the light comes on again I would read off the codes again then.

What year is your car, the 3-2-5 memory failure appears to be MY94 only for engine ECU not ABS?

Dave

[T5hug]

Cheers for the info Dave!

The car stood for 2 years before i got my hands on it but prior to getting it through its MOT it was driven about 30 miles (to the test centre of course) and definatly went over 12mph! It had a new battery prior to this. I also got the 1-1-1 code before it went in so everything seemed OK then!

As part of her reconstruction i had done a new CV joint so was concerned i had maybe upset the ABS sensor in the process. The ABS light didn't come on until i had done about 750 miles after MOT and it went back off again. I just thought i would check the codes to be safe and it threw this at me!

My biggest concern is that the ECU wont be working properly if it has no memory! Will i now have a fault free T5 everytime i start her up!?

Car is 93 with RIP pipework. is that a MY94?

[NorthlandDave]

Yep, RIP was on manufacturing year 94, can check on VIN 9th character will be R.

Sorry if this seems like a silly question but could you have read the codes off the A2 socket instead of A3 which would have been engine ECU instead of ABS, it's just I only have 3-2-5 listed for the engine ECU not ABS, might be worth checking if there are codes still stored on A3.

The memory failure code for the engine ECU just means that it failed whist the battery was disconnected/flat. As soon as it is connected to battery voltage again the memory should be working fine again.

As long as the ABS light isn't on there's no fault and its working normally, if the light is on the ABS system is not working so just normal braking. CV work may have disturbed the sensor, might be worth checking the connector and that the sensor is seated properly in the hole if you get the light come on again.

Dave

[T5hug]

Yeah the codes were taken from a2! Didn't know A3 was for ABS! I'll check A3 tomorrow though just to be safe but the ABS light has never came back on since!

Only major concern just now is the memory failure code. I had got a 1-1-1 after new battery fitted so it seemed ok! Could the ecu have a problem with a permanent supply from the battery!?

[NorthlandDave]

Yeah could be an issue with the permanent supply from the battery +, this goes to A26 on the engine ECU connector. May also be a poor contact at the battery + terminal or the ECU connector. I'd try pulling out the ECU and checking for voltage at A26 or resistance between A26 and the + battery terminal. If it's a poor connection at the ECU just removing it and refitting it could improve the connection. It might be worth clearing the codes and seeing if it comes back after a drive or few too.

Did you get any codes off A3 for the ABS?

Dave

[T5hug]

OK cleared the codes on A2 and after the weekend its showing up the 3-2-5 again. Not had a chance to check the positive feed as yet.

Checked A3 and its throwing a 4-4-4 at me!?! Acceleration sensor signal?? Not entirely sure what this is! Any idea?

Also can i ask exactly how to check codes? I thought all the codes came from A2. Can someone tell me which port gives codes and what for? i.e. A3 is ABS (thanks to Dave!) Do you check and clear codes from all the ports in the same fashion? :dunce:

[NorthlandDave]

This link has a list of all the trouble codes for each system and which socket it is on the diagnostic thing:

http://www.matthewsvolvosite.com/volvo-repair-database/volvo-850-trouble-codes/

For ABS it has 4-4-4 no power supply to valves in hydraulic unit, acceleration sensor signal is for the engine ECU.

Should be same process for each socket, except I think for power seats you have to press a button on one of the seats first:

To read the codes just plug the flylead into the relevant socket for which system you want to read off. Press the button for ~1 second and release then the code will flash out the number with a longer pause between each digit. Repeat for next code until you get first code again, then that's all of them.

To clear, all of the codes need to have been displayed and the first code has been repeated at least once. Press the button for ~5 seconds and release. Then when the LED comes on press the button for ~5 seconds and release. If you try to read the codes again as above you should get 1-1-1 if the codes have cleared. If you still get the code(s) the clearing didn't work correctly just need to try again, I sometimes get the timing off a bit and it doesn't clear.

3-2-5 off the ECU and 4-4-4 off the ABS are both power supply related, are the battery terminals in good nick, secure and no corrosion? That would be my first check before checking the ABS connectors or getting the multimeter out.

Dave

[T5hug]

OK Cheers Dave!

Like i said i thought everything was done off A2 and obviously only had the codes for that!! New battery was fitted so the connections were done recently but i'll have a check! That seems the obvious one. Also done the PCV and had to renew the washer bottle and pipework plus its had a new bonnet so plently of things around that area that could have pulled out/cut a connection somewhere!!

Cheers for all the info i'll let you know when i find out!

Shug