I now have the wiring well underway. I purchased the GD body loom and dash loom but made the mistake of getting the ls3 engine loom direct from Canems. Not that there is anything wrong with the Canems ls3, on the contrary, it is clearly a quality loom but it is missing the wiring parts that connect directly to the GD body loom via the two Round pin Lucas connectors (9 pin and 5 pin). Since I cant go back in time (which would have been my preferred choice) the only solution was to obtain the Lucas plugs (these need to be purchased as pairs even though I only needed one side). Fortunately Dave at Canems was very helpful in enabling me to figure out his loom and Luckily I have a pal with a genuine genius in electronics and what may have proved a wee problem for me, was resolved in a couple of hours between Dave and Chris. The new loom additions are now made up and terminated /labelled as well as identifying where and what everything does from the gearbox outputs, fuel pump sensors etc.
Lucas Rists 9 Way E Series Circular Sealed Electrical Wiring Connector
Reverse Lockout Solenoid
One problem I can see is that there is no real provision for the reverse lockout wiring.
Here’s the problem
Downshifting from 6th to 5th presents a distinct possibility of pushing into reverse rather than 5th. OK I appreciate that it would be very hard to push it into gear, more likely there would just be a very unpleasant grinding of gears but that still means something between a very unhealthy situation and a very nast one.
Tremec deliberately make the Reverse position very difficult to push across to to avoid any accidental sloppy driving that may event in such an outcome. and to overcome this they expect the vehicle manufacturer to adopt a control system that energises a solenoid that in effect removes the pressure required to shift across to reverse. Obviously this solenoid should only be activated when it is safe to engage reverse, so the logical control is to use the ecu and a speed sensor that energises the solenoid at speeds at or below circa 3mph.
This is not a problem for the volume car manufacturers indeed its a designed in system for safety. However this presents a problem for the retrofit market or low volume manufacturers such as ourselves because the system is not technically complete without the control from the ecu to trigger the solenoid at low speed only. It appears there are several workarounds to this problem:-
- I guess the most widely adopted is to ignore it. do nothing, just use brute force to pull the shift lever across to reverse effectively fighting against the solenoid spring.
- Wire it up to the brake switch (and/or the clutch switch).
- install momentary switch or switch on timer at the gear knob or appropriately positioned switch to engage the solenoid for a short period whilst the driver wishes to engage reverse.
There are some other variants and combinations of these solutions but in truth they all seem a compromise over how it should work. Additionally, option 1 also apparently leads to excessive wear on the shifter parts that are being forced, probably not a big issue on such low use vehicles. Option 2 is not a real safe solution since you could still be going at high speed when touching the brake and downshifting. Option 3 is just messy.
Further research suggests two better alternatives both of which allow the reverse select mechanism to work as intended.
- Aftermarket speed sensor/ reverse lockout control module such as
A couple of these units exist unfortunately they are all from the USA and run about $100. - Utilise the ECU. Trigger this from the aftermarket ECU if available. all the above device does is recognise the speed the vehicle, then allows a 12v trigger if that speed is below a set level (say 3mph). I’m not sure if this can be done from the Canems unit but I will be try to find out. It seems such a solution is possible from other ecu units such as Megasuirt, which can capture speed data and output a switch at a determined speed. such an ecu trigger output control that switches on a nitrous pump at a set speed could be hijacked and used. I’ll take this up with Dave At Canems This would be the tidiest and lowest cost solution effectively working like any mass produced car using the tremec’s. If not I’ll probably opt for the aftermarket control unit http://reverselockout.com/
Marks Cobra Build 