Y22 - idle speed control actuator '93 300TD

balge59

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hi
just reading up on testing the ELR relay, it says apply 12V across Y22 - idling speed increases - BUT - it says do not exceed 3 sec or actuator will be damaged!
Bit nervous about breaking this, it doesn't say which way round to apply the Voltage - the connector is a 'one way round ' one but it fits on either way round on the actuator...:confused:
the diagram shows numbered terminals but nothing on the actual actuator...

so
- does it matter which way I attach the battery?????
any way of actually testing the ELR directly instead?

cheers!
 

Alex Crow

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..........any way of actually testing the ELR directly instead?

cheers!

have you checked to see if there is any voltage to the solenoid terminals with cold idling engine? if you have not then you should. the solenoid will likely work either way round, but the wiring colours at the plug will give you a clue. mercedes earths are mostly brown, and live will be red, black or blue. there may also be narrower tracer colours on the wiring.
 
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balge59

balge59

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Hmm, cars too warm now, just got it up to 'hot' cos I had to fit a new thermostat - not 'refit' - there wasn't one in it!!!!!:shock:
Just checked at the connector, no Voltage (DC, right?)with a hot engine at tickover ... does that mean new ELR if there's none with a cold engine?

The wires are red/blue - from OVP to terminal 2 - and blue/brown - to the ELR from terminal 1, but as the terminals don't appear to be numbered....does that mean it doesn't matter which way round?
As I say, the terminal will fit either way! I thought it might be bodged or broken.....
 

Alex Crow

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probably either way will be fine for the connector.

the red/blue will be permanent live and blue/brown (actually brown/blue??) will be PWM earth i suppose. i had thought that these solenoids had either 12v or 0v across them - ie on or off. your description of the test procedure suggest they are actually modulated, we live and learn.
 
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balge59

balge59

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probably either way will be fine for the connector. .

ok, that makes sense

"the red/blue will be permanent live and blue/brown (actually brown/blue??)"

oh yes, I meant 'brown-with-a-blue-stripe' and 'red-with-a-blue-stripe' :Oops:


" will be PWM earth i suppose. i had thought that these solenoids had either 12v or 0v across them - ie on or off. your description of the test procedure suggest they are actually modulated, we live and learn"

We-ell I'm probably not telling it well - the only tests I've got say -

- engine idling, disconnect connector - tickover speed increases briefly,

- engine idling, apply 12V to ELR actuator - idle speed increases no longer than 3 seconds or damage,

- engine idling, disconnect idle speed should = ..hmm that says "570F40/min" -( mines ticking over about 500 RPM...) - adjust idle speed,

- engine idling, disconnect coupling and test = approx 12V
 

dieselman

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probably either way will be fine for the connector.

the red/blue will be permanent live and blue/brown (actually brown/blue??) will be PWM earth i suppose. i had thought that these solenoids had either 12v or 0v across them - ie on or off. your description of the test procedure suggest they are actually modulated, we live and learn.
I would expect it to be modulated, otherwise it will just raise the revs a set amount, which is OK for a cold start device, but I understood this was an idle speed regulator so it will need to be variable.
 
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balge59

balge59

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Ahh with you!
I won't be able to test that til I get someone to rev it while I meter it, but that makes sense...

Soon as the motor cools down I will check though - presume the ELR is duff if no power from it to the actuator?
:(

oh yes... any idea what the 'unadjusted' tickover ought to be?
 
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dieselman

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oh yes... any idea what the 'unadjusted' tickover ought to be?
No, but 500rpm sounds about right given that the control solenoid will then stabilise it to the normal 600.
 

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I understood this was an idle speed regulator so it will need to be variable.

i have observed these before, and they 'seemed' to be 'on or off' - ie raised idle dropped dramatically when coolant temp reached a certain point. i have previously thought of this idle increase as a blunt instrument, but that test procedure suggests otherwise.
 

dieselman

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i have observed these before, and they 'seemed' to be 'on or off' - ie raised idle dropped dramatically when coolant temp reached a certain point. i have previously thought of this idle increase as a blunt instrument, but that test procedure suggests otherwise.
In itself that makes sense. Most diesel pumps used to have a cold start device for increasing the idle speed and advancing the timing. The timing on these pumps is mechanical with no additional advance but this could be a cold start idle increase solenoid, in which case why only a 3 second test, unless it needs the fuel pump body to act as a heat sink.
 
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balge59

balge59

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i have observed these before, and they 'seemed' to be 'on or off' - ie raised idle dropped dramatically when coolant temp reached a certain point. i have previously thought of this idle increase as a blunt instrument, but that test procedure suggests otherwise.

hmm well there doesnt seem much flexibility, I 'think' when the actuator gets a signal, it rams up the solenoid, then when the signal changes, it just shuts back down?
Pretty on/off?
 
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balge59

balge59

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In itself that makes sense. Most diesel pumps used to have a cold start device for increasing the idle speed and advancing the timing. The timing on these pumps is mechanical with no additional advance but this could be a cold start idle increase solenoid, in which case why only a 3 second test, unless it needs the fuel pump body to act as a heat sink.

well, that kind of makes sense, if the actuator is just on/off, leaving it under full power may overheat it? or maybe bend something?
 
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balge59

balge59

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Alex Crow

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thanks for that balge, these threads really need feedback. i politely suggest you add this to your last thread, with a link pointing here.
 

Number_Cruncher

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Glad to hear that the tacho is now working.

One possibility that leaps out is that if the system hasn't been working for a while, then someone might have "adjusted" it. Perhaps it would be best to go through the idle speed set up procedure?

As for the function of these systems, they are really there to overcome the idle hunting that you always get when mechanical governors wear a bit. The speed of the control loop is much faster than the speed the engine can respond, so, the control inputs don't need to be particularly "subtle"
 
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balge59

balge59

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thanks for that balge, these threads really need feedback. i politely suggest you add this to your last thread, with a link pointing here.


Good thinking! Just for completeness, this is the other thread mentioned -
http://forums.mercedesclub.org.uk/showthread.php?t=68772

I will retest tomorrow when its cooled down, but it looks like I need a new ELR...any suggestions on a supplier?

Still not happy about chucking 12V randomly through the actuator thing, so I'll see if the new ELR sorts it out...
 

Number_Cruncher

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>>but it looks like I need a new ELR

How have you reached that conclusion?
 

teddycatkin

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hi
just reading up on testing the ELR relay, it says apply 12V across Y22 - idling speed increases - BUT - it says do not exceed 3 sec or actuator will be damaged!
Bit nervous about breaking this, it doesn't say which way round to apply the Voltage - the connector is a 'one way round ' one but it fits on either way round on the actuator...:confused:
the diagram shows numbered terminals but nothing on the actual actuator...

so
- does it matter which way I attach the battery?????
any way of actually testing the ELR directly instead?

cheers!

Send Lizzy a PM she is standing in for Malcolm tonight?
 
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balge59

balge59

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>>but it looks like I need a new ELR

How have you reached that conclusion?

Well I got no voltage across the two wires from there to the actuator when testing for the 12V feed (although the engine was hot by then), but know you mention it....hmm maybe worth testing them for continuity before getting out the wallet...:Oops:
Will check that as well tomorrow... I think I soft-boiled my brain in the sun this afternoon...
 


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