Modifying wiring loom for relays.

[KANEIT]

I have a Premier Wiring loom for my old TVR. It's a nice looking loom but doesn't have any relays, not that I expected any. Would it be straightforward to add relays wherever I chose? Looking at an example wiring loom the car only had relays for the fan and starter motor. Is it necesaary to add relays or just desirable?

Cheers.

[Dave Dax builder]

Piece of cake.
Use your regular switch to trip the relay, connect one terminal to the opp (+ or- ve) feed and run the power to your accessory from a better source through the other 2 terminals.

[KANEIT]

OK cheers for that, I'll give it a go!

[thermister]

hi KANEIT,i know you've been thinking of rewiring your M for a while now,i presume you've done some research so while choose a premier wiring loom and also just for my benefit which loom kit did you choose,also within the new loom how have you incorparated the ballast resistor for the ignition

[CorseChris]

As Dave says, it's smart to feed the relays from a new, heavy duty feed. VWP do some nice (if a bit pricey) modular units that allow pretty much any combination you might want. I used one when converting a car from it's original Motronic ECU to an Emerald - I wanted to run a single heavy duty 12V feed direct from the battery, then have this all controlled by the ECU/ignition switch. Used a HD relay that is operated by the ignition feed, this powers two strips of mini blade fuses, each of these then feeds low power services like Lambda heater and ECU power directly, or via relays for high current things like starter solenoid, coil power, charge cooler pump power, cooling fan power. Takes all the load of the original switches and puts it on cheap, easy to replace relays, and it's all neat & tidy.

[KANEIT]

thermister said:

hi KANEIT,i know you've been thinking of rewiring your M for a while now,i presume you've done some research so while choose a premier wiring loom and also just for my benefit which loom kit did you choose,also within the new loom how have you incorparated the ballast resistor for the ignition

How do, I got the Lucas uniloom. Its one piece with a separate instruments loom and is generic, not specifically for a TVR. I looked for ages and deliberated between that and the SVC one but got that as I found it looked simpler and was cheaper because I'm tight. I analysed the example pdf diagram I got from m-fix and drew up each circuit individually. I think that trying to understand what goes where bit by bit has helped me. Thinking about it now though I think the SVC one has a relay base plate already, silly sod I am. I knew I could not construct a loom but fitting one is the less complicated part I hope.
I expect to need to add circuits somewhat, such as power to the boot release switch and to my tacky starter button. All the spurs are labelled on a laminated sheet and explained in more detail on a few more A4 sheets. I haven't fitted it yet as I only stripped the old one out (DESTROYED IT!) last weekend and wired the instrument loom up.
Looking at my engine bay and an example wiring loom it looks to me as if the ballast resistor is in the +ve coil feed cable. I think it will be the white lead on the engine spur.
I am no pro believe me but think with time and advice from people on here I will get it done. My next step is to feed the loom around the car and deduce routes before cutting anything! When I'm happy that the cables are routed fine I will trim them and fit the appropriate crimp terminals.
I will need some new connectors such as the wiper box one and some watertight front lamp connectors that Hella seem to still sell. Some of the instrument connectors seem different like the bullet type on the back of the tacho.

[KANEIT]

CorseChris said:

As Dave says, it's smart to feed the relays from a new, heavy duty feed. VWP do some nice (if a bit pricey) modular units that allow pretty much any combination you might want. I used one when converting a car from it's original Motronic ECU to an Emerald - I wanted to run a single heavy duty 12V feed direct from the battery, then have this all controlled by the ECU/ignition switch. Used a HD relay that is operated by the ignition feed, this powers two strips of mini blade fuses, each of these then feeds low power services like Lambda heater and ECU power directly, or via relays for high current things like starter solenoid, coil power, charge cooler pump power, cooling fan power. Takes all the load of the original switches and puts it on cheap, easy to replace relays, and it's all neat & tidy.

You make it sound easy and that sounds a neat installation. Just searched VWP - an absolute godsend cheers!