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

[sergio]

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Voltage
I tested the power on the TB connector
between Pin 1 and Pin 2,3,4,5,6
then P2 and P3,P4,P5,P6
etc etc

voltage on TB connector Key position II

voltage on TB connector.jpg (15.39 KiB) Viewed 732 times

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Then I checked the general voltage.
As you mentioned the voltage was too low.
I have had a drainage, but this time it seemed more bizarre because it went down fast and stayed there!
This is strange; I had the meter connected AND the battery charger plugged in.
The second I turned the key to position II, the voltage went down from 12.45 to 10.00 and STAYS there. I turn the key to position I the voltage starts going up slowly.
So I began pulling out the fuses one by one to see when the voltage goes back up.
It is the cabin 10A fuse # 25 Ignition Switch, CEM, ECM .
Is this a sign to look for another car?
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[draser]

I just measured batt on my car - 12.35V which goes to 11.59V with key on 2. I admit that my batt is a little low, I don't drive the car much. With key removed voltage goes right back up.
It sounds like your batt is very low - assuming you have a second car can you take it to Autozone or similar for a test (free)? Does it crank OK?
Can you redo the TB test using the positive lead to check each pin of the connector, and having the negative attached to chassis at pass fender ground? Key on 2. Don't give up on her yet, it's just the huge lack of information that makes repair difficult. I have a Honda Accord for which I bought a factory repair manual - sold by Honda. They have repair information for all car systems, that's how I was able to rebuild the engine in the garage. It seems that they're not affraid sales will go down if they make the info available.

[precopster]

If anyone is out there with a Bosch ETA some conparative results would be handy.

The Magnetti Marelli throttles require full battery voltage at green connector. I don't have a wiring diagram to look at for your Bosch ETA but something tells me it also needs 12V (an educated hunch I supppose)

Does the wiring diagram show that 12V should be at any of the ETA pins?

If so it really looks like either is possible:

1) The ECMs power stage of the board has failed

2) The ECM is not receiving adequate voltage supply

If no. 2 is the case you need pin-out voltages at the ECM connector from the wiring diagram so you can tell if the ECM is getting adequate supply.

If ECM is getting adequate voltage and continuity from ECM to ETA is good (already verified) then the ECM is faulty.

[draser]

That's what I was kinda expecting myself to see, some 12v on some TB pin. What I saw so far was 5v voltage levels, like it is for digital circuits. But I think the TB motor will need more than that? The other thing compounding the confussion is the low batt voltage, all readings will be skewed. Also the lack of ground in the ECM connector I can't explain. You'd think you'll have a ground for the TB potentiometer feedback signal.
There are several fuses on top left of the ETA diagram, that's probably what powers up the ECM, or at least that side of the ECM. The fuses are powered by relay 2/32. There should be full batt voltage there.

[sergio]

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Checked all the 6 pins on TB vs body negative;
Pins 2 and 4 == 0 V
Pins 1 and 6 == 3.4 V
Pin 3 == 5 V

Also searched my wiring pdf, there is no detail about CEM or ECM. No schematics, no pin # to battery positive indication. "I mean no detail /no electronic map of the printer circuit / no schematics for neither CEM or ECM."

Doesn't the image, print screen of Immobilizer on previous page, indicate that CEM is OK?

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[precopster]

I thought CEM was in the clear if the criteria is that screenshot only. If the XeModex procedure is anything to go by you can forget the CEM for a while.

Right now the info we need is whether the ETA requires full battery voltage at any of its pins.

Try this: test each pin on ETA connector while a second person places ignition on ( or you could use small alligator leads to your meter)

The ECM may cut power to the ETA if the engine isn't started within a certain time period.....just a thought.

(Please note: a ECM is NOT a CEM) ECM is engine control module

[sergio]

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Ok I will get someone to help me tomorrow to see if any 12V goes into the TB. Or any change in voltage at all. But I read somewhere the 5V is the right voltage (at least at idle)

ECM-CEM I know they are not the same
Sometimes when I'm tired I speak the way I drove my Mini-Moke en ice.


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[draser]

I measured volts on my 2005, with plugs plugged-in and key on 2 (first), then engine running (second), pin to ground.
TB:
pin 1 - BL/R - 11.3V switching to 3.2V back and forth / 13.59V
pin 2 - GRN/YL - 7.9mV / 20mV
pin 3 - WT - 5V / 5.02V
pin 4 - GRN - 10.5V switching to 3.2V back/forth / 12V
pin 5 and 6 could not access.

MAF:
pin 2 - GRN - 12.37V / 14.04V
pin 3 - GRN/YL - 15mV / 27mV
pin 4 - VIO/WT - 4.9V / 5V
pin 5 - VIO - 1V / 2.1V

Obviously you don't have the 12V in your readings. If you're not able to measure the 12V like above (obviously you'll be measuring with key on 2 only), I'd go after charging the battery (so it won't drop to 10V), and check power distribution coming into ECM. I'd start with fuses at top left of diagram.

[sergio]

Hey draser, you're here already!

I just finished doing the voltage-on-cranking test. The results are surprising.
With TB connector disconnected so that I can use a needle to my multimeter the reading are exactly same as if the key was sitting on position II. No change.

Not only that, the engine is running the same way . Pushing the pedal will stop the engine from running.
But don't forget that the TB is NOT WIRED to ECM.

So, being connected or not to ECM I have the same situation. Yet there was adequate continuity on the cable.

Maybe I go back and try the MAF voltage as well.


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[sergio]

Maybe I'll try to read the voltage with TB cable connected to ECM. With the needle in the back.