Cruise control randomness

[Darren S]

Hi all,

Had various random happenings with the CC on the 182 for quite a while now. Previously, I had a long period where it simple refused to work at all and now more recently, it appears to be hit & miss.

The green light always comes on - but usually nothing happens when I try to set the speed or manually increase/decrease it. There's just the expected reduction in revs and speed when I come off the throttle as if I haven't enable the switch at all.

Yesterday on the motorway was a little weird. Green light on, set the speed at around 60mph and then incremented it up with the button to........ 69mph. Where it stopped. No more. Went to reduce it with the wheel control and it was sat firmly at 69mph and wouldn't reduce. Naturally, the instant I touched the accelerator, I had manual control again - but I honestly don't know where to begin fault-finding with this.

I changed the brake switch a while back to an aftermarket one - but there was no conclusive improvement. I really hope it's not a wiring problem as that's a world of pain that I don't want to go down. Some of the steering wheel button & switch checks that I've seen online appear to be very finicky too.

Should I approach this methodically and if so - how?

Cheers.

 

[TheBandit]

The CC signal triggers are just an amount of resistance. I would start by getting the airbag/wheel out first and checking the buttons for continuity and resistance. Alternatively you should be able to monitor the puple/back top-most pins center connector behind the wheel.

Clear = 0 ohm
Resume = 900 Ohm
+ = 300 Ohm
- = 300 Ohm

 

[Brigsy]

It will be the buttons or squib if it wont increase speed.

If it wont stay on or activate, its prob clutch or brake switch. Need to log them.

 

[Darren S]

AI was saying that the airbag was fairly easy to remove, but some parts of the process were quite fragile and delicate?

 

[Matt Cup]

Airbag can be a faff.

But even a hamfisted idiot like me managed it.

 

[Brigsy]

Airbag easy enough, just pull the fuse out for the airbag/srs systemmand remove, be careful with the wires as fragile

Check resistance at the squib wiring plug first if you dont want to remove it, only need to take top half of the cowling off

 

[Darren S]

The top cowling can be removed on its own without anything else done to the wheel, I take it?

 

[Brigsy]

Yeah just pulls off.

 

[Darren S]

OK guys - @TheBandit / @Brigsy - I'm am absolute knuckle-dragger with anything electrical! If you could run through with me what I need to actually do, please?
I've got my Uni-T UT105 multimeter to hand, with the Ω set to 2k. The top cover over the steering wheel came off easily enough and the connector shown earlier is in clear sight. Erm, now what...?

I assume I have to have the engine running to perform any form of testing - though I'm just overly cautious with the airbag situation.

Any help would be appreciated - cheers!

 

[Brigsy]

You dont need engine running or ign on. You will need to disconnect the squib connector and probe the relevant 2 wires for cruise controls and cycle the buttons with meter connected. No idea which ones off top of my head sadly

 

[TheBandit]

It's the top-most pins on this central connector, where the purple and black wires would be plugged in.

From the back it's these two pins.

If your multimeter probes are thin enough, you may be able to push them into the connector to save unplugging

 

[Darren S]

Ah, that makes sense - thanks both.

Should I disconnect the negative off the battery before doing anything of this? Like disconnecting the connector or putting it back on?

 

[TheBandit]

Personally I wouldn't disconnect the battery but there is no harm in being safe rather than sorry!

 

[Darren S]

Small delay - no 9v batteries about for the multimeter.

I'll get that sorted.

 

[Darren S]

Why are electrics so fickle??

So, with the cover off the steering wheel and the negative terminal on the battery disconnected - I thought I'd have an obvious check on all the connections in and around the squib. Nothing felt loose or out of place. I disconnected the squib itself and it looked clean. Wiped a bit of dust off the top and blew into the socket itself. No obvious debris or anything came out and then clipped it back in.

Out for a drive this evening and on the motorway (complete with a 50mph roadworks section) - I thought I'd try out the CC and speed limiter. Everything worked - flawlessly. No problems with Resume, Override, + and - either heading out or on the return journey. I don't think it's immune from misbehaving again in the near future - but it's not worked as a full system for several years now.

Just weird. No wonder I don't like (or understand) electrics!

 

[Brigsy]

Probably not been plugged in properly last time its been off. A simple poor connection will cause a host of issues on a circuit that works via resistance values.

 

[Darren S]

I'll post back on here in the coming day/weeks/months as to when it starts acting up again....