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| Hazard Lights | Rating: 
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| Posted: 11-01-2010 02:45 am |
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1st Post |
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RG Member
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I just bought a 1973, vin 13934 and set about preparing for a NY Inspection. The Hazard Light Switch had come apart so I replaced it with a good take-out from a 74 parts car. Even with the new switch the Hazards were still inoperative. I found that I did not have power to the switch. The 74's owner's manual noted that power for the hazards was supplied through a 25 amp fuse located under the dash. I searched and was unable to locate the fuse. Is this the same on a 73? Is this fuse an inline glass bus fuse or a fusable link? Or are the Hazards fused from the main (3) fuse block? I am able to get the Hazards to work if I toggle the Hazard Switch on and activate the turn signal stalk to either position. I assume the power from the turn signals are back feeding the Hazards. Thanks, Rob
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| Posted: 11-01-2010 07:11 pm |
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2nd Post |
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MikeIsotech Member 
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Hi Rob I'm currently putting my Healey back together and got the hazzard lights working only last week. You should have power to the switch - if not I'd look again for the in-line 25A fuse and check it. My car is a righthand drive and the fuse is built into the wiring loom. It's under the dash, quite close to the wiper motor. There's some wiring diagrams on line which I've found really useful: http://home.comcast.net/~jrkengr2/html/wiring_diagrams.html Good luck! Mike
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| Posted: 11-02-2010 01:25 am |
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3rd Post |
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RG Member
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Mike, Thanks for the link....the wiring diagrams and under-dash pics were a big help. Rob
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| Posted: 11-03-2010 11:29 am |
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4th Post |
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RG Member
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Found the fuse and it was okay. The Hazards will only work with the "Hazard Toggle" in the on position and the "Turn Signal Stalk Switch" in either position. They will not work only with Hazard Toggle on. Anyone have a fix? Thanks in advance.....Rob
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| Posted: 11-03-2010 02:08 pm |
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5th Post |
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Brett Gibson JH5 20497 Member
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Do the turn signals work ???, the hazard switch when turned on bypass's the turn signals and they should flash even if the key is not turned on, there should be constant power to the switch at all times, are the two flasher units mounted under the dash on the side wall any good. You really need to trace the power feed to the switch to see were you are losing it. Most connections under the dash are usually in pretty good condition, unless someone has ducked with them, alot of the troubles come from the engine bay were the wires can get corroded, brittle fraded etc, clean your grounds, check the harness infront of the radiator and clean it up, I have seen bad connections there affect the flashers even though the turn signal worked. It really comes down to making sure you have good contacts which takes time and patience. Brett
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| Posted: 11-03-2010 04:31 pm |
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6th Post |
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MikeIsotech Member
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Brett is right, the normal turn circuit should be isolated when the hazard switch is on. I'm wondering if you have problems with your new switch. I had to take mine apart and clean up the switch faces as they had oxidized with age. One easy way to check out the hazard operation is to do it without the switch. Take the switch off the connector and use a small piece of wire to link between pin 3(light-green & pink wire) and pin 1 (green & white wire) on the harness connector. That will hardwire the power to the hazard side of the circuit and remove the normal turn signal side. You should now have the hazard lights working. If they aren't it may be worth trying a new hazard unit. If they are working then you need to check out the switch. I decided to replace my old hazard and flasher units with modern electronic parts. The old electro-mechanical units are sensitive to the current flowing so don't always flash. The electronic ones are much more reliable. I got them for around $6 each and only had to add a ground wire to make each work. Hope it helps Mike
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| Posted: 11-03-2010 04:47 pm |
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7th Post |
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Brett Gibson JH5 20497 Member
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As a note, the new Lucas flasher units in my own experience are basically crap, they are a mass produced cheap product. I ended up using the old ones after cleaning them up. If you really have to replace them go to a Auto store and try and get a good quality unit even if it's a three prong unit they will still work. FYI. Brett
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| Posted: 11-03-2010 07:03 pm |
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8th Post |
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MikeIsotech Member
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The electronic one's are great - they have a proper timer inside and they so they flash at the same rate no matter what current is flowing. They fit in the same place in the harness as the original electro-mechanical units but have one extra terminal which is connected to the chassis. I linked it to the mounting screw and it worked beautifully. What was strange is that they were cheaper here in the UK than new electro-mechanical devices. A no-brainer for me: cheaper and more reliable = perfect
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| Posted: 04-03-2015 07:25 pm |
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9th Post |
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Eric Member
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I have a late 74 JH and had to fix the hazard switch. I reviewed the nice wiring diagrams by John Kimbrough and the comments in this thread. As far as I know, my car is all original, but the connections are a bit different from what has been described. Just as an FYI, on my car pins 5 and 6 power the regular turn signal circuit (switched by the ignition key), with 5 being the hot side. On the hazard circuit, pin 1 is always hot (not switched by ignition), with pin 2 powering the right flasher, and pin 4 powering the left flasher. Eric
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| Posted: 04-04-2015 03:07 am |
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10th Post |
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Screenplay Member
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Eric, Just a quick note regarding wiring. I can't offer anything specifically about the hazard switch wires, but I have mysteries regarding other wiring on my late '74 (19450). Trunk wiring (fuel pump, sending unit) look nothing like the wiring for any JH I can find. I have an earlier '74 (18059) that matches perfectly to existing diagrams, but the late one doesn't match anything I've found including diagrams for the GT. Interestingly, the tank sending unit wire is extremely long, but the wrong color for GT specs. There are even some light purple wires that are stubbed off near the fuel pump for what purpose I don't know. I posted on this a few months back but no satisfying responses were returned. It is, almost without doubt, unmodified from original but still... Were there some cars built with wiring looms not documented? Clinton
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| Posted: 04-04-2015 04:05 am |
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11th Post |
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Eric Member
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Clinton, Thanks for the info. I'm glad I'm not the only one with weird wiring! I'll take another look at my fuel pump, but I do recall seeing more wires than you'd expect there. I thought I had better post my experience just in case some other poor soul out there was as perplexed as I was trying to figure out why my wiring was so different from what had been described! Maybe near the end of production, with money running out, the factory got some wiring harnesses originally made for some other purpose and modified them to fit in the JH. Never a dull moment with this car. Eric
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| Posted: 04-04-2015 03:13 pm |
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12th Post |
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gmgiltd Member
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A few possibilities for the extra wires in the trunk of a JH as opposed to a GT. Rear screen heater Rear window washer pump Rear wiper Switch for the interior light from the hatch - I don't know if the JH had a trunk light or not. In addition to that I believe that legislation was in progress regarding rear fog lights which can only be switched on when the headlights are on - and should be extinguished when the headlights are switched off. If this was the case I would imagine it would be much easier to add a few wires to the loom rather than having to retrospectively fit them. Gordon Last edited on 04-04-2015 03:17 pm by gmgiltd |
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| Posted: 04-07-2015 06:02 pm |
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13th Post |
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Screenplay Member
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Gordon, Thanks for suggesting the possibilities. I thought about those GT items but none of the colors from the GT diagram match - not even close (from memory so I don't recall the actual colors). Friends (who are not JH owners) immediately brought up what Eric mentioned: end of production financial woes. It would be great to get the definitive answer to this type of question as it was only 40 years ago. Clinton
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