1994 850 T5/R No idea, possibly ECU? Big issues

Vera340 · Post by **Vera340** » 18 Sep 2014, 15:10

Hi

This is a very long story and I will try and get it all down in order.

Iv had the car now for around 6 years. It worked fine until an ex broke the gearbox (then fixed), the clutch (then fixed) and finally something went in the engine. When I bought the car it had a rica 304 chip and remap. My ex took it all apart without labelling it when I was out one day so I had a box of bits which I was less than impressed with.

Anyway I looked online for advise as all I could find were T5R engines. I was told that a T5R engine would fit in mine and the same ECU could be used. Well my useless mechanic tried to piece it all back together with no luck and the car ended up spending nearly 3 years off the road as I couldnt get the money together to take it to volvo. Also he lost the back cover of my remote so the batteries had fallen out.

Basically to cut a long story short I found a new mechanic (not volvo specific) who pieced it all back together and it finally started! We did the usual service bits but it seemed to take ages to want to start.

After a few weeks of running it carefully, it seemed to take longer and longer to start and then I ended up having to jump start it to run it and keep the battery charged (had a new one twice as it wrecked the first one because it was sitting around as wouldnt start properly). It would not start at all without a jump start by this time but when it was running it was smooth (a little smoke from where it was sitting) but all seemed ok and great to have it where I could at least take it on small runs.

We changed the coil, spark plugs, and dizzy cap. I went into volvo to order a new keyfob and they said i had to find one online as it wasnt an english one? so i ordered one from america and put batteries in - didnt work

This is where I am at now:
I put in in a local volvo dealership for a diagnostics. They couldnt use a machine as it was old so they spent time manually looking at it, and then came to the conclusion it was the immobiliser. They ordered me one from belgium 2 weeks ago, its come and was wrong. In the meantime the head technician came in and said it wasnt that so was looking again.
They said hes looked through it all and aparently the readings going into the car arent right, so he is now saying I need a new ECU - but hes said there is no guarantee and they dont make them anymore so I need to look around and buy one for them to fit.

I just want some good advice. I love the car and am willing to get it sorted but is it possible its the ECU as when its running its fine? Im tempted to pull it out of there and go from there.

Thanks in advance, sorry about the long post...trying to put all the info on

Post by **tryingbe** » 18 Sep 2014, 16:09

it seemed to take longer and longer to start and then I ended up having to jump start it to run it and keep the battery charged

That tells me you have a problem with the charging system (alternator, battery, and/or battery/ground cables) not the immobiliser nor ECU.

What is the voltage of the battery?
What is the voltage between the battery + end and the alternator + end when the car is running with everything turned on?

Vera340 · Post by **Vera340** » 19 Sep 2014, 01:18

We checked this and it was running 11-12 on start as this is how we knew to get a new one as the old battery which was new was faulty so got a swap

Could a crank positioning sensor be a cause?

Also we are unsure of the vacumn pipe exact plan so not sure 100% if they are correct

Forgot to mention that volvo also checked fuses and changed a few with no difference

Thanks

Post by **tryingbe** » 19 Sep 2014, 07:05

What is the voltage at the battery when the car is non running?
What is the voltage at the battery when the car is running?
What is the voltage at the alternator when the car is running?
What is the voltage between the battery + end and the alternator + end when the car is running with everything turned on?

Except the battery, none of the parts you changed have anything to do with the battery charging system, which seems to be what's wrong here.

Check engine light on? Check the codes.

https://www.matthewsvolvosite.com/read-codes-volvo-850

You need to give me the information I asked for, unless you like guess work.

so i ordered one from america and put batteries in - didnt work

If you didn't program the remote, it will never work.

http://volvospeed.com/vs_forum/topic/21 ... gon/page-2

Post by **erikv11** » 19 Sep 2014, 08:39

tryingbe wrote:...
Except the battery, none of the parts you changed have anything to do with the battery charging system, which seems to be what's wrong here.

Check engine light on? Check the codes.

https://www.matthewsvolvosite.com/read-codes-volvo-850

You need to give me the information I asked for, unless you like guess work.
...

I agree with all of this. It really sounds like the car has a charging system problem. So cam or crank sensor, ECU, vacuum lines and fuses, are all completely irrelevant to that. If you provide exact numbers from the specific voltmeter tests then you may be able to hone in on the problem. And codes.

Vera340 · Post by **Vera340** » 22 Sep 2014, 07:29

Ok great thank you well I will need to get the car out of volvo first but wanted some suggestions as they want to keep it and change the ecu with one i have to supply.
Will also check codes again and provide these so will be back with all info once volvo release the car

Post by **abscate** » 22 Sep 2014, 08:21

Ive semi-seriously considered changing my user name to "Its not the ECU" to save me typing it.

I don't know why people jump to the ECU so quickly, but looking back on this forum, I think we see about 2 out of 10,000 problems being ECU related - and those are usually after someone has messed with it.

Engine swaps, etc, of course, you have to use the right one - which takes some research.

Post by **timmybdaddyof3** » 22 Sep 2014, 10:49

ECU is the default answers shops give when they are clueless (either in general or as to a specific problem)....In our shop when we get a car with a "bad ECU" diag, the standing joke is it was probably the technician who was Extremely Confused and Un-knowledgeable.

Bottom line, if your only issue is the battery drain, and it runs fine (besides the little smoke you described, you DO NOT have an engine issue (Vacuum, ecu, ect...)
Immobilizer/alarm issues on an 850 will cause a "no start" condition
Vacuum leaks will cause driveability issues.

If ANY shop starts pointing that direction based on the symptoms you describe (battery dying, only starting with a jump) RUN, because all they are going to do is throw parts at it.

Start with the simple, and this can be easily diagnosed.
With the key off
1. What is the voltage with the between the two battery posts
2. what is the voltage between battery + and the firewall ground-strap
3. what is the voltage between alternator + and battery ground

with it running and the headlights and ac fan on.
1. what is the voltage between battery posts
2. what is the voltage between alternator + and battery -

give us these numbers and the problem (or a good direction) should surface.

Bonus round - Them making you supply the parts is tell-tail - unless I know my client very well I will not use customer supplied parts (This includes used parts - I will accommodate when a customer wants something specific, or from a specific vendor and I generally wont mark it up but if MY shop installs, its MY reputation regardless) You providing the ECU gives them deniability when it does not solve the problem....the line you will get is "we installed the part you gave us and it was bad, - you still need to pay for the labor"....From my side of the table it's complete BS, its like I tell my guys, when you make a diagnosis it better be right and complete; If your wrong your eating the parts and labor, and if you sold it wrong to the client your going to have to eat what it takes to make it right.

Sorry for the rant; I just love wrenching, I love having my own shop, and I hate morons who don't know what they don't know and expect customers to pay for them to learn...we charge $100/hour for each actual hour WORKED, not book labor; you don't pay us to guess, learn, and throw parts at it, you can do that on your own time, you pay me $100/hour to solve a problem faster and better than you can.

And I step off-my soap-box of auto shop hateing

Vera340 · Post by **Vera340** » 28 Oct 2014, 02:58

Just an update, Iv finally got the car back from volvo with much trouble as they wanted to charge £300 for something they didnt fix - finally they agreed not to charge.

In the meantime Iv changed the rotor arm and the leads as they hadnt been done so wanted to make sure it wasnt one of the small things I hadnt done.

Today we are checking all the voltages as per your guidelines, so I will upload these later today and hopefully someone can help. Thanks for all your help so far guys.

Post by **northernlights** » 29 Oct 2014, 18:48

After some recent experiences, I've come to the conclusion that due to brush and slip ring wear, the Bosch alternators in these cars slowly reduce their output, but provide enough power to (mostly) keep the car running.

Eventually it hits a wall, and the output voltage drops to a low enough level that it can't run the car and keep the battery properly charged. I would strongly advise checking the voltage regulator at the least.

Robert has some great videos about this that are worth looking at to help you through the process.

https://www.matthewsvolvosite.com/forums ... hp?t=63879