Discussion
Horn has packed up. Not a major problem in itself but the MOT is next week and no horn is a fail.
Have checked fuse and relay and both seem fine.
Have removed steering column cowling and connections/slip ring contacts look ok.
Have grounded out live lead (to button push) directly
and no noise.
What voltage should be on the red live (to button push) wire ?
Final option is the trumpets themselves (or connectors) have had it.
If so where are they and how do you access them. The picture in the bible doesn't make it obvious.
One other thought. If I get a spare battery and just connect the 12v positive terminal to the red live lead would that do any harm. At least it would confirm positive volts at the button push.
>>> Edited by over_the_hill on Tuesday 4th January 15:47
>>> Edited by over_the_hill on Tuesday 4th January 16:24
Have checked fuse and relay and both seem fine.
Have removed steering column cowling and connections/slip ring contacts look ok.
Have grounded out live lead (to button push) directly
and no noise.
What voltage should be on the red live (to button push) wire ?
Final option is the trumpets themselves (or connectors) have had it.
If so where are they and how do you access them. The picture in the bible doesn't make it obvious.
One other thought. If I get a spare battery and just connect the 12v positive terminal to the red live lead would that do any harm. At least it would confirm positive volts at the button push.
>>> Edited by over_the_hill on Tuesday 4th January 15:47
>>> Edited by over_the_hill on Tuesday 4th January 16:24
Easiest access is from underneath the front of the car which is where that picture was taken.
The horn push should be grounded but the voltage on it compared to ground depends on how the car was wired as the horn is also part of the cooling fan circuit.
Time to get power onto the horn directly and if that doesn't work then the horn units could be dead.
Steve
www.tvrbooks.co.uk
The horn push should be grounded but the voltage on it compared to ground depends on how the car was wired as the horn is also part of the cooling fan circuit.
Time to get power onto the horn directly and if that doesn't work then the horn units could be dead.
Steve
www.tvrbooks.co.uk
I understand you need a working horn 
for safety...
I've been using the same M.O.T. guy for years only had the Griff for a short time but he understands that certain cars need M.O.T.ing in a certain way...
perhaps you need to make a new friend
for the odd thing like:-
Your number plate light is a bit dim...
You have rainex on your screen do you? dont want to wash that of do we!!!...
Did i see you brake lights come on on the handbrake test? na must've been a firework outside...
Obviously all the above was on a mates car
he failed mine on a split steering rack gaiter
which he knows i will replace immediately as dont want to pay out for a new rack!!!!
for safety... I've been using the same M.O.T. guy for years only had the Griff for a short time but he understands that certain cars need M.O.T.ing in a certain way...
perhaps you need to make a new friend
for the odd thing like:- Your number plate light is a bit dim...
You have rainex on your screen do you? dont want to wash that of do we!!!...
Did i see you brake lights come on on the handbrake test? na must've been a firework outside...
Obviously all the above was on a mates car
he failed mine on a split steering rack gaiter
which he knows i will replace immediately as dont want to pay out for a new rack!!!! You should have 12v at the horn push connector, with an "ammeter" it should show 200ma when you touch to neg/chassis, do try a known neg/chassis, other than on the steering wheel. If no good, find the horn relay,pull out, look at the pin numbers and short pin 30-87 in the fuse box. This will put 12v to the horns, or should ! Given these results should give an idea of which direction to be looking, low current(horn push) or high current( relay to horns ).
david beer said:
You should have 12v at the horn push connector, with an "ammeter" it should show 200ma when you touch to neg/chassis, do try a known neg/chassis, other than on the steering wheel. If no good, find the horn relay,pull out, look at the pin numbers and short pin 30-87 in the fuse box. This will put 12v to the horns, or should ! Given these results should give an idea of which direction to be looking, low current(horn push) or high current( relay to horns ).
Good idea - shorted the relay pins and beep beep so horn trumpet OK.
No volts at horn push.
Removed cowling and no signs of a loose connection. However, at the opposite end of the ignition barrel (from the key) there are three wires, a red one (continuous 12V) and two others. Can't remember the colours on these but they were both white and something. One is ground/neg and the other switches to 12V when the key is turned.
Am I corect in thinking the red 12V connects to the horn push ? If so the break in the wire is somewhere between the barrel and centre of the steering wheel. Unfortunately I couldn't see where the wire went as it was all concealed behind the steering whhel and barrel and I didn't want to start dismantling unnecessarily.
Dont short any wire to chassis on the ignition barrel, they are all 12v + !! Input, ignition output and starter solenoid. If you take a look at the ring the steering wheel rubs against, you should find the wire, its been a while since ive been in there, is it green and black ? others will surely pop and help.
Finally cracked it last night with the help of a friend who read off the multi-meter while I had my head buried in the footwell with the probes.
Relay pins 30-87 OK (high volts) and when shorted horn sounds. Pins 85-86 (low volts) nothing at all.
Recheck fuse and this is OK. Check fuse socket and this is OK. So the problem appeared to be between the back of the fuse board and the back of the relay socket - not very likely.
As a last resort decided to go down the fuse panel and check each fuse and guess what ?
My fuse board is the 97/98 alternative as shown on p243 of the Bible, although the 6-plus-5 Relay layout is slightly different. There are spare fuses where there is a Blank showing on the bottom Relay row so mine is an alternative of the alternative.
The Horn fuse is shown as 3rd from the left - 25A shared with Fan 1. It turns out that it is in fact 3rd from the right - 25A shared with Fan 2 !! This one had come slightly loose and when pushed back in everything worked.
Should I have really expected anything any different.
Relay pins 30-87 OK (high volts) and when shorted horn sounds. Pins 85-86 (low volts) nothing at all.
Recheck fuse and this is OK. Check fuse socket and this is OK. So the problem appeared to be between the back of the fuse board and the back of the relay socket - not very likely.
As a last resort decided to go down the fuse panel and check each fuse and guess what ?
My fuse board is the 97/98 alternative as shown on p243 of the Bible, although the 6-plus-5 Relay layout is slightly different. There are spare fuses where there is a Blank showing on the bottom Relay row so mine is an alternative of the alternative.
The Horn fuse is shown as 3rd from the left - 25A shared with Fan 1. It turns out that it is in fact 3rd from the right - 25A shared with Fan 2 !! This one had come slightly loose and when pushed back in everything worked.
Should I have really expected anything any different.
Over the hill.
We have never met but today you became my new best friend.
My horn packed up about a week ago. I did exactly as you did, checked the Bible. Fuse ok, relay ok. I was about to start pulling the grille off to look for the horn (can't actually see it behind there) but thought I'd do a quick search on PH.
Voila et bonnet de douche Rodney!! My horn shares the 10amp fuse with the courtesy light! (3rd from the right on the fuseboard).
So thanks, mate. I owe you a beer.
We have never met but today you became my new best friend.
My horn packed up about a week ago. I did exactly as you did, checked the Bible. Fuse ok, relay ok. I was about to start pulling the grille off to look for the horn (can't actually see it behind there) but thought I'd do a quick search on PH.
Voila et bonnet de douche Rodney!! My horn shares the 10amp fuse with the courtesy light! (3rd from the right on the fuseboard).
So thanks, mate. I owe you a beer.
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