Voltage at starter motor solenoid

[Gary18]

Afternoon all,
This is my first post to the forum having been a member for a few years now.
Currently I am experiencing some starting issues with my gen 1.5 turbo and would be obliged if someone could confirm whether the voltage reading at the solenoid trigger connection should be 12v or the same as the main battery feed. My readings thus far range from 8.5 to just under 9.5 volts.
Whenever the car starts the motor spins over nicely, not laboured & the starter motor has already been confirmed as good.
I haven’t tried asking an OPC for this voltage reading btw.

Regards,
Gary

 

[Lancerlot]

Gary,
You shouldn't have a voltage drop between battery and starter, so you'll need to identify where the resistance is. Obviously, check all the connections and voltages either side of them. Suspect the high current terminals as these are often soiled or corroded, so disconnect them and clean them up lightly with an abrasive and WD40.

Check the engine to earth strap is making good contact at both ends and look at this and the high current cables for frays and damage.
Regards,

Clive

 

[Gary18]

Hi Clive,
Thanks for the reply & just to clarify I am not losing voltage on the main battery feed connection it is the smaller gauge (2.5mm wire?) trigger wire from the starter relay which is the problem.
I have checked the engine earth to chassis connection in the N/S/R wheel arch and that’s ok but can’t locate the other end of the lead as it seems to disappear up into the engine compartment. Would you happen to know whereabouts it terminates by any chance on the turbo engine (or is it the same for all 997’s)?
I have located the two multi wire connections in the engine bay and just need to figure out how to get them apart to look at the pins so that’s my next task but in the meantime it would be good to get a definitive number for the voltage to trigger the solenoid contact.

Regards,

Gary

 

[Lancerlot]

So, you have full voltage through the heavy duty cable down to the starter, but not through the low current operator cable, is that correct?

I seem to recall you need to dip the clutch in order to start, don't you? Could it be an intermittent fault in the clutch pedal switch, do you think?

Otherwise it might be a faulty ignition switch, cable, connector, relay or fuse.

You could try bypassing the existing circuit completely by rigging up a temporary operator cable from a power source to starter through some kind of switch (even a domestic wall a switch will do) and see if this energises the starter.

But check that pedal switch first! []

Regards,

Clive

 

[Gary18]

Hello again Clive,
In answer to your first question yes, it is the low current operator cable I am specifically querying to determine the exact voltage that should pass through here. One would think it should be full battery voltage (which I am not seeing).
Secondly you are correct in that the clutch pedal does need to be depressed in order to initiate the start circuit. I haven't run a bypass on this switch although I have tested its function and it performed ok so I ruled that out on the basis that I don't see how this can somehow reduce the voltage allowed through the starter relay. I may go back to this and install a temporary bypass for the sake of elimination purposes.
So the ignition switch (or control module depending upon how you refer to it) has been replaced along with the starter relay and the starter motor assembly has also been tested independently off the car to prove it is not at fault which only leaves me to conclude it has to be a wiring / connection issue somewhere.
Were you able to determine where the engine earth lead connects to the engine itself?
I haven't tried examining any fuses but there's no harm in doing so to simply eliminate that point.

Regards,

Gary

 

[Lancerlot]

I think I've reached the limit of suggestions for you.

It's always going to be difficult diagnosing intermittent electrical faults on a forum.

If the solenoid is not engaging the starter, suspect the solenoid. If, as you say all is well there, you must look for a reason for the voltage drop.

It's going to be process of elimination and you will need to work through it methodically. In a final analysis, it may be something quite obscure such as a partial break in the wiring harness.

No idea where the engine earth strap terminates. It's probably bolted to the block somewhere. Search for a parts schematic on the web as this may provide a clue. However, it's doubtful that's the problem though, since it's the low current cable that seems faulty and when testing, you must have used a different chassis earth anyway for your multi-meter.

Why not just connect a fresh battery up and see if that solves the issue?

Regards,


Clive

 

[Horsesoldiers]

What are the actual issues you are experiencing with starting?

 

[Gary18]

Sometimes when I try to start the car all I get is what appears to me as the solenoid click - everything else is as it should be (dash lights up normally, fuel pump works etc.) and so I have replaced the items in my reply above and know both starter motor and battery are good. I just don’t know if the solenoid trigger feed should be the same voltage as the reading for the main battery feed and that’s why the solenoid contacts don’t always work correctly.
If I am loosing voltage in this trigger wire due to a higher resistance in the circuit then I guess I will have to try point to point tracing each connector back to the power distribution board.
Any idea how the multi pin connector in the engine compartment come apart?

Regards,

Gary