Throttle body cleaning issues EPIC Volvo saga...RESOLVED!!

sergio · Post by **sergio** » 03 Jul 2013, 14:25

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No, I don't get the higher volts between ECM and TB
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Meanwhile I found an article on www.volvoclub.org.uk that says ECM are not prone to failure, that ECM have a life of 12 - 15 years....hmmm

http://www.volvoclub.org.uk/faq/EngineF ... ilureModes

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draser · Post by **draser** » 03 Jul 2013, 15:09

That's how I measured with needles in the back of connector pushed in until they stop. Basically we need that 12V voltage for this to work. I can see the end of the line in one of 2 ways: a) you find that ECM does not get the 12v for some reason and troubleshoot that, or b) you find that ECM has 12V getting into it in which case you have a bad (Xemodex to test) ECM - However, let's wait for results of your testing.

sergio · Post by **sergio** » 03 Jul 2013, 15:27

You wouldn't know by chance which pin in ECU receives the 12V

According the site I mentioned ECM's function is transform 12 V to 5V which is processing voltage and transforming 5 V to 12 V to be sent to a device (TB/Starter? etc) This makes sens. But to understand what is what and where, you need a diagram of that circuit board or at least the list of pins and their functions.
The wiring info in my book doesn't show this.

I am pretty sure I would be able to understand and find out this but only if I had the diagram on one single piece of paper (hard copy). Not in many segments spread over some150 separate pdf files.

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Post by **precopster** » 03 Jul 2013, 15:44

Lucky at ARD may also be the man to answer a question or 2 about the pin-ins and pin-outs. He does the Fast Friday articles.

He may be the man to clone another ECM for you if the verdict is that the ECM is faulty.

Perhaps you can PM him??

draser · Post by **draser** » 03 Jul 2013, 16:06

Looking at this diagram, ECM gets main batt volts on pin B:11 - fuse 11B/23 powers that. So you can measure on the fuse, negative lead to chassis always. Also there 12v on pin A:17 through fuse 11B/6, you can measure that fuse. Also fuse 11B/8 sends 12V to pedal pots. All these fuses are on the ETA page, top left.They're powered by relay 2/32 which is made by ETM. All good test points related to your problem.
As far as I know there's no internal diagram of any of the modules - proprietary info. However, all that aside, you need to duplicate my voltage tests, my car runs!

sergio · Post by **sergio** » 04 Jul 2013, 09:50

I read an article on ETA. This guy has a Mercedes and just repaired the cable to ETA.
He says "Almost all ETAs problems caused by shorting wiring inside ETA loom."
He shows wires that have been damaged by the heat of the engine.

I think I should recheck my wires again. I have checked them for continuity only, I have to check for short.
The fact that the voltage drops to 10 as soon as I set the key on position II suggests that this could be a good idea.

Maybe I will have to remove both ECU and sister TCU. Pull the connectors, cut those 6 wires going to TB, attach an extension, put everything back, remeasure the voltage and possibly make a new harness for the new wires!

IF there a short.

In case anyone wants to see and comment;
http://www.restoreyourmercedes.com/Merc ... ewire.html

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Post by **precopster** » 04 Jul 2013, 16:01

You may be on to something but have you checked voltage points at the ECM as Draser suggested? I think we're on the right track now. See the process through.

Your car's battery hasn't been cycled by proper running for months now. It may be very weak. How old is it?

You can CHECK for shorts without the guesswork. Besides if there were a short capable of dropping 12V to 10V you would be blowing fuses.

I'm not saying shorts aren't a possibility but we're talking about a Volvo P2 5 cylinder wiring loom here and not a Mercedes. Just because Mercedes use an ETA that's not evidence. Mercedes also use the same globes in their headlights; that doesn't mean Volvo wiring looms have the same problems.

With ECM removed even if you had a short on ETA loom all the wires to the ETA are out of circuit (not connected to anything) so this is how you you can compare results.

draser · Post by **draser** » 04 Jul 2013, 16:49

^ 2 Mike - I'd rather focus on what we have so far. Especially if it's simple stuff to check - like voltage on fuses, etc. However, for peace of mind, you can always unplug the ETA and test each pin to ground (batt off). By the way - how do you unplug the damn connector, I see the one lock on the outside, is there one on the other side as well? Do you have to squeeze both sides to release? I can't fit my hand in there.

Post by **precopster** » 04 Jul 2013, 18:43

There is 2 of them and be careful not to snap the other side.

If you do you'll need to use zip ties to hold it in.

sergio · Post by **sergio** » 04 Jul 2013, 20:37

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Mike,

The notion of short wires seemed plausible because the car was running prior to cleaning. Limp mode would occur once in a blue moon. So, I said maybe there were already some damages done to the wires and I worsened the situation with my bending and pulling the cable.

I checked the wires at the end point (TB connector). To test them at ECM end I would have to remove EMC, sister box (Transmission control??), pull out the connectors, cut and or attache extension wires put back the ECM etc THEN test it.

The battery is about 2 years old. Whenever I start testing , I plug it to the automatic charger (as if it were the alternator). After I'm done with "Key on position II" situation it takes no more than 5 minutes to get back to 12.60 V

All fuses (hood, cabin, trunk) are checked and are OK.

Anyways, tomorrow I will post the result

And while we are here, any idea how to pull out these sockets / connectors?
Any damage might cost more than the price of the car

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Throttle body cleaning issues EPIC Volvo saga...RESOLVED!!

Re: Throttle body cleaning issues