K-click (relay mod vs brise)

[Roger Ford]

You sure about that? 5 ohms seems way, way too much. If you put 12v across that, then the maximum current it's going to flow is 2.4 amps. That wouldn't be enough to run the car's lights, let alone the starter motor.

[TomB]

Right, this is really annoying me now. Ive just taken delivery a Ultramax battery and I still get a heavy click, like the solenoid is throwing but now immediate start. Third press, it fires. I swopped back to Yuasa /Banner and I get the same symptoms. Its very repeatable and predictable - it will always start on the 3rd or 4th press of the button - each time a loud click. FIA key/ red cables/ new starter/ relay mod as StuF earlier post all done over the winter.

 

The car is still all together so I can't get much access under the exhaust headers to be definitive, but I have two brown/purple wires which join together, the red/brown cable and the big red under there. Im expecting next to replace the coloured wires, but before Ido Id like to understand where they go. The Brown/red goes to the relay mod,where do the brown/purple go? I cant see them on the ignition barrel? I only have a main body wiring diagram for an EU2 K series, whereas the only engine diagram I have is for an EU3 and it doesn't have any brown/purple going to the starter.

 

[charlie_pank]

I think replacing the solenoid feed will fix it, there's nothing else left! To understand which wires go where, unbolt the starter and let it drop down, see for yourself which wires go where and replace appropriately!

[rjnewman]

I replaced the solenoid cable that runs from the starter motor to where it joins the loom. When I pulled out the old cable it had previously been replaced. No idea if this was a poor repair or if the cable degenerated over time. Either way I don't have any trouble starting from hot now.

 

Good luck and hope this helps

 

Richard

 

[Johnty Lyons]

The brown Blue are lighting and fuse box feeds they take power away from starter Ignore

replace the main big red cable from battery as its heat damaged and has a very high resistance giving you low voltage at battery. Plus new wire to solenoid from relay It will work.

[myothercarsa2cv]

Have you removed all cables, cleaned up the contacts, and replaced?

[David Brown]

Anyone know the size of the "big red cable" (not length)?

[Roger Ford]

That will be battery/starter cable. From memory, I think it's 25 sq.mm but could be wrong. The tricky bit with them is fitting the connectors - if you've got a local battery specialist it's probably worth taking the old cable to them and having them make up one the same.

[Johnty Lyons]

Roger is correct Connectors are very importand don't try and fit yourself if you havent right tool and you wont have cos its over 200 quid.

[Johnty Lyons]

I've just read back a few posts and am alarmed, GET rid of Scotch locks they have no place near a Caterham disastrous we buggers never ever use them especially on solenoid cct they cant pass current.

JJ

[David Brown]

Johnty, got the tool, probably got the lugs here at work but need to strip out the car to check. Thought it looked, from memory, like 16mm sq. Having had click at every hot start this weekend in NI I really need to get this resolved. Contacts cleaned, relay bypassed, solenoid cleaned, solenoid feed wire replaced. Will replace live cable and get starter checked.

[TomB]

Thanks for some tips, Ill hopefully be able to have a look this weekend.

 

One observation though is that the car is harder to start when stone cold, than when hot. Yesterday it took 8 presses of the start button to turn the starter motor, after which it started instantly. This after its left in the garage on a charger, which indicates the battery is full. I drove it for over an hour, then left it for 6 hours, then it started on the first press! The next hot start again after fuelling, started first time.

 

At home, after a week on the conditioner, it seems harder to start, than when hot. I thought the K Click was a hot start, not a cold start issue. Ill look to replace the wiring near the solenoid next, hopefully over the weekend if I dont get roped into painting the kitchen 😳

 

Could the alternator provides a better or more suitable charge to the battery (Yuasa banner equivalent) than the charger.

[TomB]

Back again! Im going to sort this over winter - my upgrade this year will be reliable starting.

 

My set up is:

+ve battery to Relay30

-ve to Relay 86

Solenoid cable to Relay 87. This is simply disconnected from the big MRFU connector, no wire cutting & directly connected to the relay.

Red white from ignition to small MRFU connector is tapped with a scotch clip and connected to Relay 85.

 

While investigating this weekend, Ive taken a new wire from the solenoid to Relay 87 to bypass the existing wire and eliminate any problems in the loom and unplugged the injectors so I don't suffocate myself in the garage.

 

The starter cranks quite well on the first press of the button, but the next press, all I get is a click from the solenoid with no cranking. A few presses of the button with solenoid click, and then it cranks after about 4-6 presses.

 

I know the scotch clip is still there, but its on the low voltage feed from the ignition switch to the relay (white/red wire), and when I have the click, its from the solenoid, like its not getting enough power to fully throw it. As such to my mind the scotch clip connection from the ignition switch isn't affecting it. I can cut the RW wire if necessary and directly connect it to the relay, but Im not sure it would make a difference. I don't like making permanent wiring changes, but Ideally Id like to get the terminal from the small MRFU connector, but I cant see a way of extracting it.

 

The fact the solenoid clicks when I press the button suggests the start switch/ ignition feed is ok.

 

Ive replaced the external relay with a 40amp today incase the 30A contact were burnt, but its still as before.

 

Could the way the FIA switch is connected effect the solenoid?

 

Im also wondering if its voltage drop/ battery related. Ive just fitted a new Red Top 25, so the battery is fine - I think my next step is to attach a heavy red lead direct from the battery to the starter to remove the FIA key from the equation. Im wondering if removing the long cables and FIA key will help - if its does, Im not sure what the next step will be as both long cables & FIA key were replaced last year.

 

Its hard work this problem.

 

[Stationary M25 Traveller]

Put a meter across the battery when doing all the tests.

 

Have you cleaned and checked all the earths .... to chassis and engine.

 

All the connectors can be removed from plugs. Unplug it then look at the face of the plug. Some have a yellow shield that you have to pull out then look for the release tag for the individual connector.

[Roger Ford]

Quoting TomB: 

Red white from ignition to small MRFU connector is tapped with a scotch clip and connected to Relay 85.

A Scotch Lock? I thought you wanted reliable?

 

(Although having said that, mine had a Scotch Lock there too for quite a while, and it seemed to work fine. However if I'd still been having problems that would have been the first thing to go).

[TomB]

The only reason Ive kept the scotch lock on the low power switched feed from the ignition is that the bypass relay seems fine - I can hear and feel it activate without solenoid and battery feed into the relay. Correct me if Im wrong, but my understanding is the low voltage feed just needs to be sufficient to trip the relay and feed the battery to the solenoid. If this is happening, then it shouldn't make a difference to the current reaching the solenoid.

 

Im going to remove the exhaust to allow good access to check & clean all connections, then Ill look at earths. Does the earth on the front right of the engine have any relation to the starter system?

[Stationary M25 Traveller]

All the fat earth cables are relevant ..... twixt battery, engine and chassis.

[TomB]

As a general electrical question, without the earths being clean and conductive, there will be a poor circuit back to the battery. Does this mean the battery voltage will drop more between presses, meaning less umph in the battery for the next press?

 

If pressing the button puts a slug of +ve into the solenoid, and then there is a poor return to the battery, where does it all go? And will this mean less return for the battery to use next press?

 

Not investigated earths yet, but am trying to work out in my own mind why they are important. Come to think of it, I don't think I've had the short braided earth off front RHS of the engine for a couple of years.

[TomB]

Thanks for the email Jonathan

[Stationary M25 Traveller]

If there is a poor earth return, there is no circuit ..... therefore no 'slug'

[Roger Ford]

Quoting TomB: 

If pressing the button puts a slug of +ve into the solenoid, and then there is a poor return to the battery, where does it all go? And will this mean less return for the battery to use next press?

 

A poor earth has a high resistance. Effectively you've got two resistances (the solenoid coils and the earth) in series, which means the voltage is divided between them. If you have, say, 9 ohms resistance in the solenoid coils and 1 ohm in the earth, then the solenoid will "see" 10.8 volts and the earth will see 1.2 volts. The lost power (at 200 amps it would be 240 watts in this case) will disappear as heat in the earth lead or connection.

 

Because you're wasting some of the power, there will be less left in the battery afterwards, though probably not significantly less than if was working properly.

[SLR No.77]

Tom, I'm pretty sure that in the emails we've had going back and to you said that "hot-wiring" the battery to the solenoid enabled the car to start consistently every time? If this is the case you do not have a bad earth but still have an issue with how you are getting your positive feed to the starter solenoid.

 

Stu.

[TomB]

Good point Stu, Id forgotten that. I had a play earlier - when the solenoid was directly connected to positive, the starter cranked quite happily. But after a few contacts and cranking, the cranking didnt slow down, but it clicked and nothing else happened.

 

The red battery cables & FIA key were replaced last year, so how can I be loosing power along the long positive run to the FIA key?

 

I have just had a thought that before I pull the loom to pieces - I should remove the FIA key and long cable runs from the circuit and directly connect the battery to the starter with some spare red battery cables or jump leads. This will highlight whether I have a problem on this part of the circuit.

[Stationary M25 Traveller]

Elimination ..... step by step ....... methodical.

 

Get rid of the connection to the tiny little relay in the MFRU ..... it could be dragging down your 12V

[TomB]

You mean cut / disconnect the red-white wire into the MRFU that I taped with the scotch clip. If the bypass relay is tripping, wont the high power be sent to the starter?