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Another wiring question

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Beans
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Re: Another wiring question

Postby Beans » 18 Mar 2020 10:44

If switch is fine and there is a current over the switch to the relay,
but no current from the relay to the lift motors,
either the live feed to the relay or the relay itself is faulty.
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1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

http://www.tr7beans.blogspot.com/

oliviertr7
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Re: Another wiring question

Postby oliviertr7 » 18 Mar 2020 12:23

I experienced the same failure, and it was due to the corroded lugs of the relay, so follow the instructions of mrBeans
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Chubster
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Re: Another wiring question

Postby Chubster » 18 Mar 2020 16:37

Hi Beans, the relays have tested as good, it is with the live feed however trying to find the reason for the absence of the live feed is the problem. Everything checks out with the flash circuit and with the main switch all have current, it just disappears by the time it gets to the relay. Corrosion is not an issue as the loom/ harness is new and the headlamp connectors are also good.

Beans
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Re: Another wiring question

Postby Beans » 18 Mar 2020 18:29

If I understand it correctly the switch feed is reaching the relay and activates it?
And with the feed circuit for the lift motors activated nothing happens (= no current towards the motors)?

I read your problems with the new loom. Have you tried finding a live feed when the light is switched on.
And I presume you checked all wire colours are correct?

Another problem might be the lift mechanism not returning properly.
To find this out, very carefully to turn the knobs underneath the lift motors with ignition on.
This might activate them. Take care that you don't get trapped so work from below only!!!
Image
1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

http://www.tr7beans.blogspot.com/

Chubster
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Re: Another wiring question

Postby Chubster » 18 Mar 2020 19:03

Hi Beans, yes you are correct in your thinking. If the main switch is off there is current on the down circuit, when you operate the main switch to 'on' the pod down current disappears as it should, however, there is no pod lift current. I can simulate the absent current by using the power probe and when I do this the headlamps continually cycle up and down until the probe/ current is stopped. At this point the lamps return to the down position.

I have checked everything I can think of and everything checks out, wire colours paths etc. One of the red headlamp plugs had been wired incorrectly and had caused the headlamp diode to expire, I have changed the unit for one of my spares and although the pod now works I have not been able to resolve the issue.

I have a spare Pektron unit which I will swap out just to see if this makes any difference, its a real PIA head scratcher. :D

oliviertr7
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Re: Another wiring question

Postby oliviertr7 » 18 Mar 2020 20:08

for information, there are also small diodes inside the headlight motor.
if these no longer work the headlights stay up or down.
or a little oxidation on the slats

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Rich K
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Re: Another wiring question

Postby Rich K » 18 Mar 2020 20:25

There is a circuit breaker in the headlamp circuit that is normally located behind the fuse box. It is a small black rectangular object with two wires attached (brown from memory). Some years ago my headlamps were not raising and it turned out that this circuit breaker had failed. Replacing it cured the problem.
Rich.
1980 TR7 drophead now repainted and started refitting plus V8 upgrade
1977 TR7 fixedhead awaiting restoration
1981 TR7 drophead bodywork now done, mechanicals next then final paint
Ford Ranger Wildtrak
Jaguar XKR Supercharged

Rich K
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Re: Another wiring question

Postby Rich K » 18 Mar 2020 20:30

Item shown on Rimmer Bros website
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67E440AD-96D9-4D47-B5DF-B4A715300A1D.png
67E440AD-96D9-4D47-B5DF-B4A715300A1D.png (37.81 KiB) Viewed 4185 times
1980 TR7 drophead now repainted and started refitting plus V8 upgrade
1977 TR7 fixedhead awaiting restoration
1981 TR7 drophead bodywork now done, mechanicals next then final paint
Ford Ranger Wildtrak
Jaguar XKR Supercharged

busheytrader
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Re: Another wiring question

Postby busheytrader » 19 Mar 2020 08:55

Rich K wrote:Item shown on Rimmer Bros website


Back in the 80's I replaced the carpets which stopped the headlight pods from lifting entirely.

Why? This small circuit breaker had fallen from the loom and lodged behind the new carpet in the passenger footwell. It was bare friction fit to the wires around the fuse box area on my DHC.

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