Fitting Vectra/Omega Cruise Control to Elan M100 - If you want to use a Senator/Carlton one, I can't help you!
Firstly, my thanks and appreciation go to the guys on a Vauxhall Forum who did the ‘thinking’ on this for fitting the unit to a Cavalier – I have unashamedly pinched their circuit diagram, but modified it to suit my fitting in the Elan, and the wire colours I used.
My rationale was that if they can fit it in a Cavalier, then I can fit it in an Elan of the same vintage which used Cavalier (Astra G / Callibra) wiring and instrumentation.
Parts Required:-
Omega/Vectra Parts:-
• Control Unit / Motor Assembly including Mounting bracket and Throttle Cable. (Astra4 mounting bracket may be easier to fit than the Omega/Vectra one)
• Indicator / Dim / Dip / Cruise Switch (Left Instrument Stalk)
• Clutch switch (Twist in type required, as Cavalier brake Switch, must be normally closed)****** not easy to fit to an Elan - see later text on the way round it/
• Loom or connectors and short wires from each item above.
Lotus/Isuzu/other parts:-
• Bracket for fitting Cruise cable next to Throttle cable (easy to make out of 3mm aluminium - fits to same bolts as current throttle cable, but a tad lower and forward (has to be lower due to bonnet line). & suitable fitting for throttle plate.
• Wiring cable/connectors etc…. I bought some 7 core tow-bar wiring cable for running from dash to ECU, and used a single wire for ground. Most joints were just soldered and heatshrinked (heatshrunk?), with the odd red Scotchlok to splice into current wiring where I couldn’t easily reach with a soldering iron.
Firstly (having decided on the location of the unit), I connected the 7-core cable to the appropriate wires on the Vauxhall ECU plug (I actually did it via a seperate 8-way waterproof plug/socket, but you don't need to - I thought it might make the wiring a tad easier, but it didn't really help much!)
The only place I could find to mount the Cruise Control ECU/Motor was inside the FOS wheel arch – but that means that the OE cable isn’t long enough, so it needed to be adapted (as did some other parts)…..
I did consider fitting it where the boost transducer is currently located (and use the Vauxhall cable), but decided that it *may* interfere with the bonnet shutting, so decided against it (the boost transducer can go further down the clamshell nearer to the engine mounting – or anywhere else that the wiring/vacuum pipe will reach, or can be extended to get to).
The inner cable has a 5mm barrel end, which is the same as a bicycle gear cable,
so off to Halfords to buy a stainless universal gear gable/outer. I needed to use the Vauxhall outer cable end to connect to the CC ECU, so had to carefully remove the cable outer, whilst leaving the plastic fitting intact – then simply fit the plain cable outer into the fitting with epoxy resin – final length to be determined later depending on cable routing.
At the throttle end, I was fortunate enough to have a complete assembly on a spare engine, so just used the cam lever/wheel which I had to chop the endstop bracket off. Then it simply went onto the spindle next to the already fitted throttle cable, so I have 2 parallel fittings. If you can’t get a spare one, then you will need to make up some sort of lever system to do the job!
The Vectra mounting bracket had to be adapted (read, beaten with a hammer and chopped with an angle grinder) to get it how I wanted it – but there is just the right amount of metal in the bracket to fit exactly in the space. I had to drill 2 x 6mm holes into the suspension upright longeron frame flange (not load-bearing, so not a structural issue – also gives a good earth for the brown wire from the CC ECU), and the other end simply fitted to the lower outer pedal-box bolt. This is a captive bolt which goes through the bulkhead and holds the pedal box, and can be simply undone enough to slide the CC bracket into place, then do it up again. 2 off M6x16 bolts and flanged nuts held the other side to the longeron. It is rigid and supported in the location (I was concerned that if it wasn’t mounted firmly, then any vibration may affect the ‘constant’ speed requirement due to cable flex).
The plastic wheelarch liner needs a bit of adjustment – just warm up the affected area with a hot air gun and push it into place – it will mould itself to the required shape. BE CAREFULL NOT TO BURN YOUR FINGERS – THE PLASTIC GETS HOT – I found out the hard way that it would be a good idea to do this whilst wearing gloves to hold it in place as it cools.
Ensure that there is enough space to slip the ECU up into the bracket (there should be!), and it will be held to the bracket with 3 off M6x16 bolts/washers.
With the wheelarch work completed the cable needed routing and connecting to the Clutch, Brake and Control switches and the Speed Signal.
By using a single 7-core cable it kept it all tidy, but as it can’t be seen, it isn’t actually necessary.
It routes straight through to behind the dash, and then gets divided into 2 main bits – 4 wires to the control stalk, one to the rear of the instrument panel (Speed sensor) and 3 to the pedals… A constant (ignition fed) 12V can be found anywhere you like, and also the earth – there is an earth braid just above the CC ECU location, hence why I used a separate wire for it!
The speed input wire that you want is a black/yellow wire from the back of the instrument panel (it goes to the ECU) and it is easiest to just splice the White wire in the 7-core cable onto it with a Scotchlok.
The ignition controlled 12V that I used was from the unused AC blower fan relay socket under the dash cover – just used a male spade connector and inserted it into the socket for the relay (Light Green wire with Green trace). Join to Green in the 7-core – with a 5A inline fuse, and also to pin B on the control stalk – unless you want to get 12V from somewhere else).
The Green/Purple wire at the brake switch is the one to Scotchlok to the Black in the 7-core cable…. It isn’t at all easy to get at, you can feel it, or see it, but it’s hard to do both – perseverance is needed.
Okay, onto the control stalk – as well as the ‘standard’ main plug connector for all the Elan stalk functions, your ‘new’ stalk will have 4 wires going to a small socket. If you are fortunate enough to have got the plug bit that goes with it, great – but if not, just chop off the socket and join the 4 wires singly.
You will notice that the 4 wires from the plug look similar colours, but they have different trace colouring – which (co-incidentally by amazing good fortune, blind luck or actually sort of thought about intellect!) are also the colours of the 3 wires in the 7-core cable .
As such, the wires connect:-
Black/Red (Pin A) goes to Red
Black/Brown (Pin C) goes to Brown
Black/Yellow (Pin D) goes to Yellow
Black (Pin B) goes to 12V from wherever you get it – I used the same 12V supply from the AC relay socket.
However, if you didn’t get the plug with the stalk, then the 4 wires on the socket (stalk end of the connection) are not the same colours as above and equate to:-
Grey (Pin A) goes to Red
Blue(Pin C) goes to Brown
Green (Pin D) goes to Yellow
Red (Pin B) goes to 12V from wherever you get it.
Oops, forgot to mention the obvious…. You need to route the wires for the stalk up through the steering column cowling!
One more wire to go, and then we’re done. This is the one which takes a bit of ingenuity (or you could say bodgery, adaptation or just hopefulness)…
The unit relies on a number of factors to enable the Cruise Control to work – the speed signal not only sets the unit at the desired speed level, but also ensures that CC can’t be set at too low a speed (approximately 50kph/30mph). Also, that the unit switches off if the brakes are applied. The final bit is that the unit switches off if the clutch is depressed.
This is basically to stop the engine revs rapidly rising when you dip the clutch. It relies on a constant 12V to be seen at Pin D on the CC ECU, and the clutch switch interrupts this signal, and turns off the unit. The switch is closed when the pedal is up, and opens when the pedal moves (opposite to the brake light switch), and in a Vectra is fitted to the pedal box above the clutch pedal (one of these). However, the Elan doesn’t have the wiring to fit it, and the pedal box isn’t designed to accept one….
The options are to find some way to fit a Vauxhall switch, and attach the wiring to it, find an alternative (one of these?) and fit it somehow, find any suitable release-to-break switch and mount it (something like a smash-glass-to-sound-fire-alarm thingy??)…….
…….OR…….
If you think that you will never dip the clutch whilst the unit is on (I can’t remember ever doing it in any of my other cars, but maybe I have), then you can just connect your Blue wire to a 12V feed and it’ll all work fine…..
…but as I didn’t trust myself (or any other driver) to remember to switch it off before operating the clutch, I decided that a simple reed switch would do the job.
I had some lying around from a set of shed alarms which I bought ages ago from the Pound shop, so they didn’t cost me anything – just make sure that you get the NO (Normally Open) type, not the NC. I fitted the main bit to the pedal box, and the slim magnet to the pedal lever with double-sided tape. There are about a million and one options on Ebay, but any hardware store will have them – they are just window/door alarm contact switches and are as cheap as chips
UPDATE – I have since bought one of these reed switches – far easier to mount, and a flat magnet just sticks to the clutch pedal.
Circuit Diagram
Pin out
The only thing I may do in the future is to wire up a dash telltale (I don't have one on my Vectra, so am used to CC without one) - my 'knowledge' of things is such that I *believe* that when you press the Increase button on the stalk to set the CC, it sends 12V to the ECU, now I am unsure if this is a constant 12V or a short 'spike'. If it is a constant 12V then the telltale is just connected to this wire - if it's a signal spike, it can still operate a relay, but the wiring is a tad harder.
There is a suitable space in the current line of telltales (as would be used in the Japanese market cars for a hot cat) and it would be a simple job to make up a suitable mask to fit the hole, plug in a spare bulb/holder, and put a wire in the blank space in the plug (up by the wire we took the speed signal from earlier).
At the moment, I can't be bothered to worry about the wiring for it, as it will need the instrument panel to be taken out to do the telltale, so it'll wait until i next have to take it out (if ever).
The mask will be a simple picture printed onto clear acetate with a standard InkJet printer - it all depends on your quality of printer as to if it will work, and if the black is dark enough to not show any light through - who knows?