speedo reads revs!
Discussion
At idle the speedo needle moves with engine speed - pretty much the same as the rev-counter. I can't test the car at speed as it's untaxed, uninsured (for the road) and un-MOTed. Any ideas?
I've got the dash out but hadn't fiddled with the speedo or rev-counter wiring. Things seemed to improve when I disconnected and reconnected the battery, then restarted the engine. I'm guessing it's just cross-talk between the two signals - and now I've separated the speedo and rev-counter signal wires as much as possible. But in case that does't work, anyone see this before?
It's quite disconcerting seeing the mileometer click round with the car at idle!!
I've got the dash out but hadn't fiddled with the speedo or rev-counter wiring. Things seemed to improve when I disconnected and reconnected the battery, then restarted the engine. I'm guessing it's just cross-talk between the two signals - and now I've separated the speedo and rev-counter signal wires as much as possible. But in case that does't work, anyone see this before?
It's quite disconcerting seeing the mileometer click round with the car at idle!!
Thanks both, I've now fixed this.
In the cable-tied loom behind the instrument panel the speedo and tacho signal wires are cable tied together. At one point the tacho cable was actually wrapped around the speedo cable. A loop in a conductor is one of the best ways of inducing a signal in a second conductor passing through the loop - and this is what was happenning. Having sperated the two the speedo now reads '0' at idle
As a Brucie bonus I took the car out for its MOT for the first time in 8 months and it passed! With the sun out! Here comes summer...
In the cable-tied loom behind the instrument panel the speedo and tacho signal wires are cable tied together. At one point the tacho cable was actually wrapped around the speedo cable. A loop in a conductor is one of the best ways of inducing a signal in a second conductor passing through the loop - and this is what was happenning. Having sperated the two the speedo now reads '0' at idle
As a Brucie bonus I took the car out for its MOT for the first time in 8 months and it passed! With the sun out! Here comes summer...
Sam Gamgee said:
Eek! So I gotta take out the dash to fix this orrible little problem? Is this easy? Have got bible but you guys more hands on, bible excellent gen. tho...
Assuming it's the same thing, yeah. Take the steering wheel off, remove the plastic column cowling, and undo the two bolts (13mm) holding the top end of the column to the underside of the dash. DO NOT remove them completely - just undo them enough to let the column drop as far as it'll go, whilst still resting on the bolts - otherwise you risk placing too much strain on the plate where the column passes through the firewall behind the pedals and breaking the watertight seal/GRP or worse. Remove the two cross-head screws under the speedo/tacho holding the instrument panel to the dash.
Remove the stereo and root around behind the left hand side (a light and small mirror may come in handy) to see if there is any fastner securing the left hand side of the instrument panel to the dash (none on mine). If so undo it (don't drop it!). Now let the fun begin...
The instrument panel will ease out - BUT it's curved slightly, around the driver, so it will want to straighten. Ease one side at a time, or top/bottom/middle - whatever wants to come. Most importantly, take care not to scuff the leather, or you'll kick yourself. Some people recommend applying polish (leather polish I presume?) to the dash to reduce the friction on the edge of the instrument panel. I say go easy and use blunt utensils - eg knives if necessary to raise the panel off the leather and allow it to slide out. It's also worth resting a towel over the steering column/centre console so you've got somewhere to lie the dash face down. There should be enough slack in the cabling to get it out and maybe even seperate the speedo/tacho cables in situ. Otherwise you'll need to disconnect the 6 or so electrical connectors connecting the instruments to the loom.
As far as I could see, once in the loom, the speedo and tacho wires run seperately, so the issue most likely lies right behind the instrument panel.
Good luck - you'll probably need two pairs of hands for refitting. Go easy - you don't want those instruments to break away and fall out!
>> Edited by griffter on Friday 10th June 12:45
>> Edited by griffter on Friday 10th June 17:18
RAW-SEWedge said:
Nice description Griffter would you mind if I included it in the tech tips section of my website ?
Warks-TVR
Dave have a page on my site The Dash Change that has info etc on getting the dash out and the switch panel. Happy for you to link to that if you like
BB
http://thegriffithpages.com
RAW-SEWedge said:
Nice description Griffter would you mind if I included it in the tech tips section of my website ?
Warks-TVR
Please do - I've now fixed spelling errors! Sometime (probably over winter) I'll get around to writing up the whole story - chassis/suspension resto, engine bay, minor body work, interior refurb, electrics overhaul and a million other jobs - all in a single garage. I've got masses of photos - should make quite a log. Don't hold your breath though, I've got a lot on this year!
griffter said:
Nice description Griffter would you mind if I included it in the tech tips section of my website ?
Warks-TVR
Please do - I've now fixed spelling errors! Sometime (probably over winter) I'll get around to writing up the whole story - chassis/suspension resto, engine bay, minor body work, interior refurb, electrics overhaul and a million other jobs - all in a single garage. I've got masses of photos - should make quite a log. Don't hold your breath though, I've got a lot on this year!
Thanks
Ballistic Banana said:
Nice description Griffter would you mind if I included it in the tech tips section of my website ?
Warks-TVR
Dave have a page on my site The Dash Change that has info etc on getting the dash out and the switch panel. Happy for you to link to that if you like
BB
http://thegriffithpages.com
Thanks BB. I'll include a link with Grifters info and send you a link to mine if you want to do the same.
griffter said:
Sometime (probably over winter) I'll get around to writing up the whole story - chassis/suspension resto, engine bay, minor body work, interior refurb, electrics overhaul and a million other jobs - all in a single garage. I've got masses of photos - should make quite a log. Don't hold your breath though, I've got a lot on this year!
If you do, and you need somewhere to host the info then you can have an ID on my website and subbmit it directly to the site.
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