4.0 Non starter . Help appreciated!

[Mr Ben]

Good evening, PH’ers

I’m hoping your collective wisdom may save me calling out an ‘expert’!

I’m the very proud and happy owner of my first TVR, a 97 4.0.

Bought in the height of this summer I’ve had a completely trouble free and enjoyable first few months.

This evening, hoping to fire her up and give it a quick wash, it started as usual, revs dropped so tried to catch it on the throttle but it died. Tried to restart, but nothing.

Locked, unlocked, deactivated immobiliser, fuel pump primes, then nothing on the final turn.

Lots of reading and shot to Halfords to get Jack and axle stands in preparation of investigative works, I’m hoping for some suggestions on likely culprits;

Battery good, everything working (light, boot release etc).
Immobiliser seems to dis arm, as said fuel pump primes and I’m sure I can hear a relay clicking under passenger side dash.

Tried rocking back and forth in second, banging underside of dash in passenger side etc..

First port of call, check starter motor connections?

Thanks in advance!

[s p a c e m a n]

Simple diagnosis is does the battery light dim when you turn the key? If the light dims then it's drawing power so it probably is the starter motor, if it's not dimming then it's something between the key and the motor.

[Mr Ben]

s p a c e m a n said:

Simple diagnosis is does the battery light dim when you turn the key? If the light dims then it's drawing power so it probably is the starter motor, if it's not dimming then it's something between the key and the motor.

Thanks very much, I’ll check that in the morning!

[Mr Ben]

I should add… when I say nothing happens, there’s no cranking, just completely void of any activity on the final turn… battery light stays same once 2nd click of ignition reached.

Thanks

[miniman]

First thing to do is put a boost pack on it. I know the battery appears ok, but it doesn’t necessarily mean it’s ok. I had one on conditioner all winter - all the lights etc worked fine but it wouldn’t turn over. Boost pack on, fired straight up.

[Mr Ben]

miniman said:

First thing to do is put a boost pack on it. I know the battery appears ok, but it doesn t necessarily mean it s ok. I had one on conditioner all winter - all the lights etc worked fine but it wouldn t turn over. Boost pack on, fired straight up.

Bugger! Really hoped that was going to work!

[Belle427]

Could be the immobiliser on the starter circuit but i would start with a check of the battery terminals for cleanliness, if thats good then starter solenoid wire on the starter itself.
They can corrode or become loose, a test lamp would be handy for you for testing which you can make up from a headlight bulb, ideally something that loads the circuit with about 5 amps and some wiring.
Can be used then to check if the starter solenoid is receiving its voltage.
Well worth doing for a visual indication if your testing on your own.

Edited by Belle427 on Saturday 11th October 07:20

[PabloGee]

It could easily be the immobiliser, and with the right info, it’s very easy to isolate it as a test.
PM me with your email and i can pass on the details.
You will need to take off the dashboard top, then it will help if you can identify which immobiliser you have.

None of this requires you to lift the car.

But since you've bought the bits, you can test the starter motor by applying a clean 12v to the starter motor solenoid (the small wire with a spade connector), if still nothing, apply 12v with a jump lead to the big red cable on the starter motor.
In both cases make sure the gearbox is in neutral, and disconnect the king lead between the coil and the distributor - you don’t want the engine actually firing up!

My guess is still the immobiliser though. I had similar behaviour until I solved it

[Mr Ben]

She's alive!

What a faf.... a complete conundrum made all the more challenging due to interference in the form of 'previous repairs.

With limited (none) electrical experience my involvement stopped short of confirming battery good, all connections ok, and power to starter motor.

I booked and this morning my knight in shining armor (Ralph @ TVS Auto Electrician) arrived.

The previous immobiliser had been replaced with a META unit, together with Toad alarm which controlled the alarm and central locking only... no immobilisation.

Power to the starter and starter working as proven by cranking with the probe.

Immobiliser circuit to fuel pump etc working.

No crank from the ignition. Ignition switch and relay confirmed working.

There had been a starter button installed but the sapde connector to the starter had been cable tied away. Why was this never connected?

Lots of head scratching and with dash removed found the speed control box from ECU was unplugged at all 5 pin connections. The speedo/milometer had been working prior so possily these (very loose) wires had come out when removing dash. We digress..

By passed immobiliser, still nothing??

So ignition switch working and power to immobiliser, fault deduced to be broken wire between immobiliser and starter!

Connected push button start wire to starter motor and bingo, she fired straight up on the push button... still not from key,

Connected ignition wire to push button loop and now have both methods to start car with immobiliser still functioning.

I dont really understand what I've typed above but suffice to say all is well.

We found the wiring diagram/colour map from an old Pistonheads thread, so together with your help, previous PH knowledge and the bible (and Ralph), conundrum solved.

Thnaks!!

[PabloGee]

Well done!
Sounds like a reasonable amount of aftermarket fiddlery going on there.
There is a brilliant set of wiring diagrams that show a lot of the original wiring. I put it on a facebook group a while ago:

https://lookaside.fbsbx.com/file/TVR%20Chim-Griff%...