ICE Electrics

[Harry Flatters]

'98 Chimaera 450 electrics!
Before I dive headfirst into the passenger footwell, does anyone know which fuse might control the switched ignition supply to the ICE multiplug? There's no clue from the fuse panel diagram.
It's the green wire (at least, it is on my car). I managed to short this yesterday and now the radio is caput! Definitely the supply as opposed to the radio. 0 volts with ignition on or off.
Here's hoping!

[Belle427]

Will be quicker to just test across each fuse in place with a test lamp.

[DVR V8]

Hi, what i would do is sit in car start it up and do a full function test and see what else is not working as probably shares fuse with something else.

[Steve_D]

Fuse 17.

Steve

[Harry Flatters]

Update - Resolved

I'd persuaded myself that there was either an inaccessible in-line fuse somewhere in the loom or there was a fuse in the main block that was solely for the ICE.
WRONG! I'd just finished wiring an alternative feed and thought I'd do a full systems check and guess what - the ****ing indicators don't work!!
So I guess we've found the ICE fuse chaps. It's #15 (in a '98 450), in case anyone else would like to know.
Changed #15 20A and indicators working again along with original ICE switched ignition feed.

Thanks for all the suggestion.

[Polly Grigora]

Harry Flatters said:

Update - Resolved

I'd persuaded myself that there was either an inaccessible in-line fuse somewhere in the loom or there was a fuse in the main block that was solely for the ICE.
WRONG! I'd just finished wiring an alternative feed and thought I'd do a full systems check and guess what - the ****ing indicators don't work!!
So I guess we've found the ICE fuse chaps. It's #15 (in a '98 450), in case anyone else would like to know.
Changed #15 20A and indicators working again along with original ICE switched ignition feed.

Thanks for all the suggestion.

A 20 Amp fuse for indicators is far too big

2 x 21 watt + 5 watt side repeater + 5 watt max instrument cluster warning light = 52 watt

Ohms law tells us 52 watts = 12 volts x 4.333 amps

Indicators draw 4.333 amps + unknown ICE current draw which is likely to be low as it's for powering up rather than driving the amp

Ooooh, 20 amps fuse is now reading as huge

Indicator and ICE cables are likely to be 8.5 amps max rated

[Harry Flatters]

I also felt that 20A was OTT for those circuits, but this and every other fuse layout I found, including the one in my own handbook, all showed 20A.

Worth mentioning that the wiper delay relay is also on this circuit (as per diagram)

One day when I'm feeling like another adventure, I'll dive down the footwell again!

[sixor8]

Polly Grigora said:

A 20 Amp fuse for indicators is far too big

2 x 21 watt + 5 watt side repeater + 5 watt max instrument cluster warning light = 52 watt

Ohms law tells us 52 watts = 12 volts x 4.333 amps

Indicators draw 4.333 amps + unknown ICE current draw which is likely to be low as it's for powering up rather than driving the amp

Ooooh, 20 amps fuse is now reading as huge

Indicator and ICE cables are likely to be 8.5 amps max rated

Except that with the hazards switched on, wouldn't there be 6 x lamps on simultaneously?

[Polly Grigora]

Harry Flatters said:

One day when I'm feeling like another adventure, I'll dive down the footwell again!

Harry Flatters said:

Worth mentioning that the wiper delay relay is also on this circuit (as per diagram)

Oooops, a big mistake on my part, should have checked before posting

Harry Flatters said:

I also felt that 20A was OTT for those circuits, but this and every other fuse layout I found, including the one in my own handbook, all showed 20A.

Ok then will start again, better be safe than sorry

The following diagram although not exactly the same as your cars circuit does tell us that fuse 15 supply to the intermittent wipe relay does in fact carry 1st speed wiper motor current when the relay momentarily energises to take the wiper motor out of its park position



Wiper motor could draw in the region of 5 amps at start-up

Moving on

Indicators draw 4.333 amps + unknown ICE current draw (say 1.5 amps) = Approx 6 amps

+ approx 5 amps (could be a little less or a little more) wiper motor 1st speed start-up = 11 Amps

Ooooh, a 15 amp fuse is more than enough to safely fuse the above circuits

BUT

Too many unproven figures though due to not knowing the exact wiper 1st speed current draw at start-up when screen is dry

and unknown ICE current draw

Damn, an ammeter and TVR Chimaera are required to prove the above

Ammeter is sat beside me at present but a TVR Chimaera is nowhere to be found

[Polly Grigora]

sixor8 said:

Polly Grigora said:

A 20 Amp fuse for indicators is far too big

2 x 21 watt + 5 watt side repeater + 5 watt max instrument cluster warning light = 52 watt

Ohms law tells us 52 watts = 12 volts x 4.333 amps

Indicators draw 4.333 amps + unknown ICE current draw which is likely to be low as it's for powering up rather than driving the amp

Ooooh, 20 amps fuse is now reading as huge

Indicator and ICE cables are likely to be 8.5 amps max rated

Except that with the hazards switched on, wouldn't there be 6 x lamps on simultaneously?

Hazard flashers shouldn't require the ignition to be on so as to operate, hence they shouldn't be connected to fuse 15

Good thinking though

[Harry Flatters]

Polly Grigora said:

Hazard flashers shouldn't require the ignition to be on so as to operate, hence they shouldn't be connected to fuse 15

Good thinking though

Indeed, hazards along with the alarm appear to be on fuse #6.

[Polly Grigora]

Harry Flatters said:

Indeed, hazards along with the alarm appear to be on fuse #6.

Ok then

Something strange that has been on my mind for several years is the fact that whoever designed the electrical system used 3 fuses for the wiper circuit when 1 would have done the very same job, yet the side lights weren't fused

[bobfather]

According to the SH Bible there are seven variants of the fuse/relay board, I'm sure there are similarities between variants but you should be cautious of assuming fuse numbers quoted here being the same across all variants

[Harry Flatters]

Agreed Bob, that's why I was clear about stating my year and model in my OP.

I very nearly made a mistake exactly for this reason by referencing the wrong layout.

I can confirm that the following layout was provided in the handbook for my car, a '98 450 Chimaera and as you can see, fuse #6 shows as Hazards and Radio Memory, not Alarm and Immobiliser, which on my car is fuse #12. Oh I do like a challenge!

[Polly Grigora]

This

is surely a record

[David Beer]

Polly Grigora said:

This

is surely a record

Hey penny, maybe he changed his “handle” as well. !!

[Harry Flatters]

Polly Grigora said:

This

is surely a record

Does this trouble you then?

FYI I have spent much of the last 20 years as Caterham 7 owner and consequently spent most of my forum time on Blatchat. I registered on PH back in 2002 purely as a curiosity, but since then primarily used it as a resource when buying and selling cars.

Since selling the 7 and buying the Chimaera, this room and TVRCC TVR Torque have been my main TVR tech resources.

PS - That's 9 now

Edited by Harry Flatters on Wednesday 6th April 20:30