2009 mitsubushi colt 1.3 strange intermittent fault

[JustALooseScrew]

Penelope Stopit said:

If you mean this above diagram, don't understand why the diagram should be wrong

Diagram is correct, it shows a resistor in parallel with a relay coil, the resistor is there to stop a back EMF of 100 plus volts reaching the Engine ECU relay control circuit

Many relay cases show the resistor when fitted


Here's more from 12 volt planet


https://www.12voltplanet.co.uk/relay-guide.html

None of this has anything to do with protecting the relay contacts

I know that

The above details make sense though now you've posted that link. I can see how a high value resistor would absorb some of the high voltage due to the collapsing EMF.

It's a hole in my knowledge that has now been filled. I was taught to dump it back into the coil using a diode.

Everyday is a school day

[GreenV8S]

Penelope Stopit said:

None of this has anything to do with protecting the relay contacts

The comment may have been referring to providing a flyback circuit for the switched inductive load - which would protect the relay contacts.

[Penelope Stopit]

GreenV8S said:

Penelope Stopit said:

None of this has anything to do with protecting the relay contacts

The comment may have been referring to providing a flyback circuit for the switched inductive load - which would protect the relay contacts.

Yes relay contacts were mentioned in a post and thought it best to mention them again in case of possible confusion

[Penelope Stopit]

JustALooseScrew said:

know that

I can see how a high value resistor would absorb some of the high voltage due to the collapsing EMF.

Of the opinion that every day is a learning day

A low value resistor will do the job and very likely quicker than a higher one yet have never carried out the test to prove this but it does add up

Problem is that a low value resistor will draw more current which would defeat the wiring in of a relay to a certain extent, depending on what was being used to control the switching

Reckon there are many here that don't post to the techie topics as they know it all inside out and it bores them to tears, it would be good if more members did post to them.....life is a learning curve and many of us enjoy learning or being corrected

[robbocop33]

Sorry,never checked back on replys!Putting correct,new relay in,the car is dead,doesn't crank at all!Short the two pins on the relay box and the car either runs perfectly,or like a bag of spanners!
I never got to the bottom of it.
The two wires that go to the ecu in the above original diagram of mine,neither show voltage with ignition on!

[Penelope Stopit]

robbocop33 said:

Sorry,never checked back on replys!Putting correct,new relay in,the car is dead,doesn't crank at all!Short the two pins on the relay box and the car either runs perfectly,or like a bag of spanners!
I never got to the bottom of it.
The two wires that go to the ecu in the above original diagram of mine,neither show voltage with ignition on!

Does seem to be an immobiliser problem but.......