R300 Engine Wiring....... Help Please

[darren f]

R300 with battery master switch.

 

Symptom is: Tried tonight to crank the engine for oil pressure prior to initial start-up. All seems ok, immobilisor bleeps etc, upon turning ignition to position 2, starter engages / disengages / engages /disengages and so on ☹️ ☹️ . Doesn’t turn stop until ignition returned to Pos 1.

 

Have wired up as per Caterham verbal instructions (Assembly guide next to useless) namely:

 

Battery +ve:

Red master switch lead (26-6 connector)

Single large brown lead from engine loom (with 10-6 ring connection)

 

Battery –ve:

Five black wires together in insulation tape wrapping

Black heavy battery lead to bolt under cam blank plate on engine (won’t reach suitable starter bolt)

 

Starter Solenoid:

Brown with red trace, female lucar connected onto male spade on solenoid

 

Stud and bolt connector on solenoid:

Heavy Red lead from master switch

Double brown lead with 10-8 holed connector from engine loom

 

Oh and I have connected the purple - brown (white trace) ECU supply.

 

Am I missing something obvious here? Any ideas at to a solution?

 

Please help…………… (desperate to get something done this weeked!!)

 

 

[Johnty Lyons]

Just a guess but sounds like a flat battery the current reguired by the starter is pulling the voltage so low that the solenoid is dropping out as soon as it drops out it releass the drain so re-energises.

Sorry can't offer any more help not familiar with that config and master sw.

 

jj

N.I. L7C AO.

Membership No.3927.

[Fred]

Black heavy battery lead to bolt under cam blank plate on engine (won’t reach suitable starter bolt)

 

i think you will find you have used the longer one for the engine earth. swap them over

use the longer for battery to top starter

 

Stud and bolt connector on solenoid:

Heavy Red lead from master switch

Double brown lead with 10-8 holed connector from engine loom

---

 

Double brown lead with 10-8 holed connector from engine loom connect this one to + on battery

all brown on + side of battery.

 

[Julian Thompson]

And furthermore, if your earth isn't good enough (and I would hazard a guess that the cylinder head is a very bad place to take a high current ground from due to things like head gaskets) then this would have the effect that all the electrics work fine and the battery is fully charged but the high current feed like the starter only gets a low voltage and behaves like the battery IS flat.

 

Ground to your bellhousing bolts, and then bond the engine to the chassis from the lower LHS engine mount to the spare (metric) thread in the block.

[darren f]

Thanks guys- a few things to try this morning.

 

One question- why is the solenoid / starter engaging continously at position 2 on the ignition. Is this a sympton of the possible poor grounding or is something actually physically incorrect? (Is the master switch wired wrong? 🤔)

[Johnty Lyons]

Right by position 2 you mean before the spring loaded position which I take it is pos 3. Pos 3 should be a white and red wire which goes to the spud and nut on the solenoid , there should be NO other wires on this spud and nut. I'm not sure of your descriptions but it may be that you have somethiong else on there and if pos 2 is your ign feed position i.e. ign light on hp pump running then you definatly have a wrong wire on the solenoid. The pre engaged starter works by a + feed from the ign sw pos 3 point [against spring pressure] energising the solenoid which when it travels fwd closes the main contacts to supply main battery power from heavy red wire to starter motor the heavy red wire is normally the only wire on the starter motor itself , but recently I have come across a number of cars where the alt output is connected here to avoid the long run up to the battery+ terminal. No real problem just that it can get very hot down there on a K and I prefer to keep as many wires away from that location as possible. As Jules sys the normal config for the Batt - is longer black wire from batt- to nearest bell housing bolt normally the top one on the exhaust side and the engine earth to chassis from the induction side engine mount cap head screw to the chassis bolt on the robber engine mount.

Have luck!

 

jj

N.I. L7C AO.

Membership No.3927.

[darren f]

Ok, progress thus far:-

Re-routed earth lead (battery to block) to go under starter motor bolt, so in accordance with assembly guide. No difference to solenoid in-out-in-out at position 2 problem.

 

Have since tried connecting direct to solenoid spade connection (low current)direct from battery - solenoid engages, stays in and turns engine over lovely. So solenoid and starter are fine, but there seems to be some problem in maintaining the solenoid engagement with the normal wiring set-up.

 

The problem with it happening at Position 2 on the ignition switch was remedied by moving some of the connections at the rear of the switch barrel. Moving a thick white wire from Pos 2 to Pos 3 made the switch operate the solenoid correctly, however I now have no dash ignition lights *mad*.

 

6 hours and the help of two qualified electricians have got me nowhere. I feel a call to Caterham suggesting they send someone out is on the cards!! BTW the wiring diagram was as much use as much of the assembly guide i.e. minimal. *mad*

 

 

[darren f]

Post Script on this one (and a record for the archives ):

It turns out to be white/pink and white/red wires transposed in the 6-pin MFU plug. After an hour or so figuring out how to get the pins out of the plug, I swopped them round and hey presto an ignition switch that does what it should and when.

 

Better still, checked everything out, got some oil pressure and she fired up at second time of asking *smile* *smile* . Much joy for me, I guess the neighbours weren't best pleased (10.00 last night 😬).

 

Now then, tonights job is bleeding the cooling