Bypassing The Immobiliser (Ignition Only)

[Belle427]

I would just replace it with the same size and see how it goes.
Maybe the solenoid is getting a bit lazy, keep some spare fuses in the car.

[blitzracing]

The 20 amp fuse will be for the solenoid supply and not the starter motor itself. 20 amps should be fine as suggested.

[ITVRI]

Tyre Smoke said:

I was told by Carl Baker that 20amp is at the limit because the car starting draws a lot of current when cold.

I would guess your current draw has pinged the fuse. It wouldn't hurt to go 25/30amp I think.

However, I'm no auto electrician and you may want another opinion.

I recently had my 20 amp fuse constantly blowing. I contacted Carl who installed my upgraded Meta alarm 8 or so years ago (l mention this as he would know the upgraded wiring etc capabilities) who suggested I could go to up 25 amp which cured the problem of the fuse blowing but not the starter engaging. In my case the underlying problem was the starter motor which was replaced.

[Polly Grigora]

Graham-9pi8w said:

Would normally be cautious about raising fuse amps in fear of causing other more serious issues.

What do others think?

I know that up-rating a fuse in a circuit that had been working fine for many months is a dangerous way of avoiding getting to the bottom of the problem

You're lucky though

Even though fuses shouldn't be up-rated, the circuit you are having the problem with relies on 100% driver input to operate it

If you were to up-rate the fuse and sometime in the future the starter solenoid didn't operate when turning the key to the start position, quickly release the key and there won't be a big problem caused by the up-rated fuse that may not have blown

Fault comes across as starter needing to be reconditioned if wiring to solenoid is good and not shorting to earth anywhere

[Graham-9pi8w]

Thanks for these recent responses guys.

So I'm wondering what I should do next.

Option -1
Leave things as they are and have some fuses at the ready and perhaps check out the existing starter motor. And how do I check the condition of the starter motor?

Option -2
Take out the "Hot Fix" mod and wire in the "Bypass" mod.

Option -3
Replace the original suspect wired (factory) immobiliser

[Graham-9pi8w]

I'll start again as pressed wrong button and posted before finishing!! 🤬

Thanks for these recent responses guys.

So I'm wondering what I should do next.

Option -1
Leave things as they are and have some fuses at the ready and perhaps check out the existing starter motor. And how do I check the condition of the starter motor?

Option -2
Take out the "Hot Fix" mod and wire in the "Bypass" mod.

Option -3
Replace the original suspect wired (factory fitted) immobiliser with a more up to date immobiliser. Advice for type/maker and fitter around the West Midlands area?

Once again thanks in advance for any advice.

Graham

[Tyre Smoke]

Go option 1 with an uprated fuse and see how you go.

If that blows, new starter time. I wouldn't mess with the wiring unless you have to.

[Polly Grigora]

Does your insurance company insist on the car having a Thatcham category 2 immobiliser fitted or a category 1 alarm

[Graham-9pi8w]

I'll have to check out my insurance but I suspect not having an immobiliser will have an effect on my cover and ultimately the premium.

Cheers, Graham

[Polly Grigora]

Ok then

[blitzracing]

Is the 20 amp fuse part of the hot start kit? Its pretty simple, all it does is put a relay in place of the starter solenoid so it can switch power directly from the 12v supply to the solenoid bypassing all the ignition switch and immobiliser wiring route. The latter all has to work as should still to energise the relay in the first place. If the fuse is part of the hot start, your problem is purely the hot start kit / wiring or the solenoid. If the 20 amp fuse is part of the TVR fuse box, that's more serious as the fact you have a hot start kit should seriously reduce any current drawn on the TVR loom and wiring to the starter.

[Tyre Smoke]

20 amp fuse is taken from the live feed into the fuse box before any of the TVR fuses. It should be in an inline holder to the relay.

[Polly Grigora]

Graham-9pi8w said:

Hi all, I've just experienced a cold start problem with my 2001 Chimaera. I had a "hot start" problem with it when we first purchased the car back 16 years ago and I fitted the "hot start" kit which solved the problem at that time.
This week I went to get started but whilst all electrics were obviously working ok, turning the key through to start position was nothing, no noise what so ever... dead!
After reading this subject from the early posts, I was expecting a problem with my immobiliser. However on checking in the battery compartment footwell and finding that the main 100 amp fuse was good, I checked the "hot start" 20amp fuse and found that it had blown.
I replaced the fuse and she started straight away, however I wonder why this fuse had blown, am I going to get further problems as has been suggested in previous posts regarding the poor TVR factory starter wiring system.
I'd be interested in what others may think about my experience.

Cheers to all, Graham

OP does mention the in-line fuse above

[blitzracing]

In that case it goes 12v supply to fuse, and then relay contacts and to the solenoid. That only gives you the wiring in the hot start kit, possibly the relay ( although un likely ) , the solenoid its self or the spade connection to it as points of failure.

[Tyre Smoke]

Spade connectors are my favourite. All that heat and humidity.

[Belle427]

We do love a good hot start kit debate
It’s usually connected directly to battery via the fuse, mine blew twice whilst it was fitted with no issues found.
I chose to remove mine and create a new 30 amp circuit using a spare relay base in the fusebox and new cable to the solenoid just to tidy things up.
May be time to remove the starter and check the solenoid isn’t sticking, it can be removed for cleaning and light lubrication.

[Graham-9pi8w]

Thanks for everyone's input.

I think I'll see how things go having fuses handy and if it happens again, I'll remove starter motor to check it out.

Will report back if that's the case. 🤞

[Polly Grigora]

Solenoid has a pull-in circuit of 2 coils and a hold-in circuit of 1 coil

Crank circuit fuse can overheat If solenoid plunger takes longer than it should to travel the distance of the solenoid orifice, 2 coils are drawing current through the fuse until the plunger reaches the end of its travel and switches off the pull-in circuit

[blitzracing]

Polly Grigora said:

Solenoid has a pull-in circuit of 2 coils and a hold-in circuit of 1 coil

Crank circuit fuse can overheat If solenoid plunger takes longer than it should to travel the distance of the solenoid orifice, 2 coils are drawing current through the fuse until the plunger reaches the end of its travel and switches off the pull-in circuit.

Not seen this on an RV8 starter ? All I can see is a single coil that pulls in the plunger and then pushes on a second plunger that closes the contacts to the starter as the first plunger reaches the end of its travel ? I've done a resistance check at full travel and the coil resistance remains constant all the time ?

[Polly Grigora]

blitzracing said:

Polly Grigora said:

Solenoid has a pull-in circuit of 2 coils and a hold-in circuit of 1 coil

Crank circuit fuse can overheat If solenoid plunger takes longer than it should to travel the distance of the solenoid orifice, 2 coils are drawing current through the fuse until the plunger reaches the end of its travel and switches off the pull-in circuit.

Not seen this on an RV8 starter ? All I can see is a single coil that pulls in the plunger and then pushes on a second plunger that closes the contacts to the starter as the first plunger reaches the end of its travel ? I've done a resistance check at full travel and the coil resistance remains constant all the time ?

Hello matey, I get where you're coming from and understand how you carried out the test

Yes, you've proved that there's a single coil permanently in the circuit

The second coil is wired between the very same ignition switch crank solenoid terminal and the heavy copper terminal that the motor connects to

The second coil is switched off when the main contacts make due to it then having a positive at each end of it rather than a positive at one end and a negative through the motor at its other end

The above is something unknown by many and is nothing to be ashamed of

Appreciate your honesty mate, many wouldn't ask