Joe_H
Well-Known Member
I repeat, when you refer to 10.5v what are you referring to - battery on load or off load.
andyfreelandy
Well-Known Member
Joe, it cranks at 10.5 volt and starts fine with a feed from the battery to the solenoid. It is only when I use the car circuitry (alarm and stuff circuits) to feed the solenoid that the clicking occurs. Like the alarm relay is dropping when it should not and with a battery voltage perfectly capable of starting the car. There is a 'threshold' voltage related component that is a weak link. It is probably design and not a fault at all. I am purely trying to solve this for all. Maybe an under bonnet press button for the cold weather that supplies the solenoid directly.???? !!! I think earth faults are eliminated by the positive 'false feed' working o.k. If the earth was at fault this would not solve the problem. Thanks guys
andyfreelandy
Well-Known Member
Was just replying - you both came in together !!!!!
blue beasty
Leaks an prone to bits dropping off
I'm kinda aware of that but if the solenoid clicks all the right connections have been made but there is insufficient voltage.
If the battery is sufficiently charged then the primary starter feed circuit has high resistance or poor earthing....
Probably...
andyfreelandy
Well-Known Member
Yup - I agree. it is just that I think the circuit design has a weak spot in that the voltage is not being passed through by all the intermediate stuff.
Joe_H
Well-Known Member
Hi Andy, sorry mate but I am struggling following you..
I take it you are saying 10.5V ON CRANKING - if so this is ok - if off load, then the battery is captain cooked
When you say - connect the lead from battery to solenoid - to which part do you refer ?
Are you talking abou the large high current solenoid feed or the small solenoid engagement feed terminal ?
The immo circuit energises a relay that allows that allows the starter solenoid low current circuit to activate.
If you are feeding the LOW current solenoid engagement supply and it turns over then the problem is in that circuit.
If you are feeding the HIGH current solenoid supply and it then works then the issue is in the high current feed from the battery to solenoid.
If it is the low current side, then check the starter solenoid relay terminals (the relay FEEDING the starter solenoid). (also - which model / year is is to confirm )
andyfreelandy
Well-Known Member
Thanks Joe, will try to answer your points - sorry to confuse.
10.5v cranking, but only when I run a lead from the same battery + to the small spade on the solenoid. If I use the car electrics and the path through the alarm it clicks when the battery is down to 10.5v cranking. Will try isolating the starter solenoid relay and false feeding that - this should show where the 'fault' lies. But as I say - I think it is a design fault causing widespread battery replacement. Maybe, for example, the alarm immobiliser needs 11v to provide output and the car would start with 10.5v ???? Further investigation necessary.
10.5v cranking, but only when I run a lead from the same battery + to the small spade on the solenoid. If I use the car electrics and the path through the alarm it clicks when the battery is down to 10.5v cranking. Will try isolating the starter solenoid relay and false feeding that - this should show where the 'fault' lies. But as I say - I think it is a design fault causing widespread battery replacement. Maybe, for example, the alarm immobiliser needs 11v to provide output and the car would start with 10.5v ???? Further investigation necessary.
andyfreelandy
Well-Known Member
There is another clue in this !! Looking at RAVE circuits, the engine immobiliser feeds the instrument pack. When this 'clicking' and none turning over occurs the trip mileage counter resets to zero and the fuel gauge dives to empty - instantly, like the module feeding it has shut down. Looks like it has !!! I need to feed the engine immobiliser module with a variable voltage supply and measure when it exhibits the symptoms. If it is at a voltage above 10.5v then I've cracked it !!!
andyfreelandy
Well-Known Member
Anyone got a circuit of what is on the engine immobiliser circuit board??
Car is a TD4 2002, but guess they are all similar??
Car is a TD4 2002, but guess they are all similar??
Joe_H
Well-Known Member
Thanks Andy, that is clearer.
It is not unusual for a battery to drop to even 9.5V (ish) during heavy load starts even with a high CCA battery.
The immo feed comes from the CCU (body computer) to the starter relay - from there it passes to the starter solenoid.The solenoid would not click at all if the fault was immo related so you can rule that out.
I suspect a simple corrosive issue in the circuit. Dont forget ohms law Andy.
I - V/R = Current = Volt/Resistance -
Given a constant (non design!) resistance due to corrosive or other contamination in a connection in the feed circuit then a higher battery voltage on cranking gives higher current to the starter solenoid, as the battery voltage during cranking decreases - with a corrosive or other contaminant related resistance, then the current to feed the solenoid must drop also. - hence only clicky clicky.
The starter solenoid takes quite a whack of current as it has to push the pre-engage lever into place and then finally shove the shorting plunger to short the large current terminals to feed the starter itself.
Joe
andyfreelandy
Well-Known Member
All sense Joe, but if the immobilisor was sending out a low or 'pulsing' feed to the starter relay (such that it chattered) then surely the solenoid would follow with click click??
Joe_H
Well-Known Member
Dont need it andy - here is a diagram of the td4 starter circuit for the solenoid.
The immo is not the issue - the click click is simply the current varying as the load is applied to the solenoid due to a bad connection. As the load is applied, the solenoid starts to engage, this pulls the voltage down due to a bad connection resistance. This then causes the solenoid to drop out and then the voltage rises - a form of oscillation.
A bit like a VCU causing traction then dropping it as the shafts speeds equalise lol (ignore the vcu reference if you havent read the nut job thread)
The energise for the starter solenoid relay comes form the ecu on this model - not from the ccu - but that is of little consequence.
Your issue will most likely be in the relay contacts of R102.
Or, the feed from R102 to the solenoid small tag.
Attachments
andyfreelandy
Well-Known Member
Will construct false feed to starter relay (isolating immobilisor) and make it adjustable voltage !!! Then measure volts when the solenoid fails to firmly energise.
andyfreelandy
Well-Known Member
Have you got what is actually on the immob board?? Just seen your PM me note !
Joe_H
Well-Known Member
Didnt send a PM note Andy ???
Please do not mess with Immo circuits etc - simply check the relay connections - and relay in the above diagram Also the appropriate fuse connections - we know the fuse is ok - what you need to do is check the connection are clean.. The fault will be simple. Please do not over complicate it. It is not an IMMO voltage related issue - it is a connection issue almost certainly due to slight corrosion.
andyfreelandy
Well-Known Member
Yup - will do. I was referring to your kind PM note on your posts about you having circuit diagrams and stuff !
Will remove and clean relay contacts and check all associated wiring and connectors. Many thanks for your time today....
Will remove and clean relay contacts and check all associated wiring and connectors. Many thanks for your time today....
Joe_H
Well-Known Member
Ah, sorry, no worries - I understand - yes - if you need anything just let me know.
Also check the earth connection for the engine bay fuse box containing the starter relay - basically, the earth connection from the starter relay. This is common(ed) with other earths as well in the engine bay fuse box. That could also be an issue..
This is where a good test light comes into play.
Have fun
Joe
Nodge68
Well-Known Member
I have come across this in the past. That time it was a burnt contactor in the starter solonoid.
I measured nearly a 2 volts of drop through the factory wiring. This was sufficient to stop the contactor from making correctly, stopping the starter from spinning. However using a short jumper cable reduced drop at the solonoid to nothing, so giving enough current to hold the contacts firm.
A starter solonoid service kit sorted out the problem.
I measured nearly a 2 volts of drop through the factory wiring. This was sufficient to stop the contactor from making correctly, stopping the starter from spinning. However using a short jumper cable reduced drop at the solonoid to nothing, so giving enough current to hold the contacts firm.
A starter solonoid service kit sorted out the problem.
andyfreelandy
Well-Known Member
Theory is sound ! Still keen to know what is actually in the immobiliser circuit (that would allow that level of volt drop) with the current drawn. I'm thinking, by the loss of fuel gauge and trip data (as these are fed from the same pcb) that the circuit is shutting down at a higher voltage than that required to turn the engine. Have a solenoid repair kit to fit anyways. Just trying to resolve this as the winter will surely bring it to a head ! Fully charged battery gives no probs....but it ain't right. If the battery can turn the engine, then the designed circuits should do it too.
Nodge68
Well-Known Member
If your solonoid is clicking, then the immobiliser is allowing the starter to turn. Check the voltage on the starter trigger lead, while trying to crank the engine. If the voltage is much below NBV then that could well be the problem.
If the solonoid contactor isn't passing the current to the starter motor. It can still burn the current off as heat in the solonoid instead. This can give you a substantial voltage drop, but not spin the starter.
If the solonoid contactor isn't passing the current to the starter motor. It can still burn the current off as heat in the solonoid instead. This can give you a substantial voltage drop, but not spin the starter.
