Ignition switch wires are hot

[mike w]

Last night I was driving home from a local cruise night and when I reached under the dash to activate my garage door opener I inadvertantly touched the wires running to my ignition switch and they were very hot.....I could not touch them without burning my fingers. This does not seem right. Does anyone have any suggestions what would cause them to be so hot?

[Rome]

I had a similar thing happen to me when I reach under my headlight switch

[MTSCustoms]

what gauge wires are they?

Check your grounds, or maybe there is a very small short somehwhere but I bet that would pop a fuse if there was..

Again, check all your grounds if theres too much current and not enough ground the wires will get very hot, also if they are very small gauge and you have a lot of accesories then they will get very hot also.

[mike w]

I don't have any accessories, just the basics. The car has an E-Z Wire Harness so I assume the wire guage should be the correct size. I guess I will start by checking all the grounds.

[skullandbones]

I'm not familiar with the EZ harness but from what I've seen with the ads on the other harnesses, they seem to be pretty much the same when it comes to the basic body harness design for a carbed vehicle. Try starting at the battery and see if the cables are excessively warm. I ran two cables to the engine from the rear and then a braided cable from the bellhousing where the negative cable is attached through the firewall to the 2x2 crossmember and through bolted for an additional ground and also for the computer (to insure EFI sensors were all getting a good ground). The main feed wire from your battery should have a, I think, 50 amp breaker installed. All the ones I have seen strongly recommend that breaker between the battery and the ignition switch. Also, if you have a battery cable with a loose end anywhere in the system, it will create a ground out or if still partially connected will cause the wires to overheat usually near that connection but keep spreading until something fails. If you have all factory battery terminals that would be less of a possibility. Then check the resistence on each individual ignition wire. WEK.

[trichardson]

I'm not familiar with you harness but it's probably the correct gauge. I'm guessing you have a bad connection. If the heat is localized near a connection (the entire wire isn't hot) then you probably have a bad crimp where the wire connects to the ignition switch or a bad switch. If the connector can be removed easily that's your culprit. Otherwise it's probably the switch. If the wire has been hot enough for long enough you'll have to cut the end off and crimp/solder a new connentor on.

[mike w]

The system that I have is for a carbed unit. I think that i need to start looking at all of the grounds first.

[MTSCustoms]

The system that I have is for a carbed unit. I think that i need to start looking at all of the grounds first.

Most importantly check the ground for the battery, and engine. These should both be AT LEAST 4gauge wire and well grounded to te chassis. If the battery ground is weak then anything grounded to the chassis isn't makin a full connection to the negative of the battery, and if the engine ground is weak them the alternated is not making a dry good ground

[IEMRacing]

Most importantly check the ground for the battery, and engine. These should both be AT LEAST 4gauge wire and well grounded to te chassis. If the battery ground is weak then anything grounded to the chassis isn't makin a full connection to the negative of the battery, and if the engine ground is weak them the alternated is not making a dry good ground

Is your cooling fan powered through that switch?

The fans pull big amps....

John

[AC Bill]

I had a similar thing happen to me when I reach under my headlight switch

If you are using a headlight relay, there should be very little power running through the switch itself. The Taurus headlight switch could handle the amperage on it's own, or the standard toggle switch can be switched out for a high amp capacity unit. Probably still best to add a relay.

Mike, you better get that fixed ASAP! I wouldn't run it till you get it figured out. There is no way, that those ignition switch wires should get hot enough to burn your fingers.

[rich grsc]

I doubt it has anything to do with grounds. As trichardson said most likely the connection. Heat will is created by resistance in the wire or connection, so a bad crimp or loose connection will heat up. A bad ground would not necessarily cause heat at a different location.
I have noticed every post about wiring starts with 'check grounds', I have never found a ground problem on any wiring issue on my cars.

[CraigS]

My thinking is that you may need some relays in your system. I have no experience w/ your harness so this is just a guess. From many posts here about electrical problems I have a general feeling that way too many high amp items are wired directly through a switch. You mention that it was at night, so your headlights were on I expect. Your rad fan may have also been on if you were in any traffic. My point is that those two items may be 10-15 amps each. Neither should be running thru your ignition switch. If you have any documents from EZ, hopefully a wireing diagram, look to see what is run through that switch. The fact that those wires were hot enough that you couldn't touch them scares me. Properly done wireing should have NO noticeable temp increase.

[skullandbones]

Mike, you better get that fixed ASAP! I wouldn't run it till you get it figured out. There is no way, that those ignition switch wires should get hot enough to burn your fingers.

Great advice!

You need to do some troubleshooting because all the speculation in the world may not help. Here is a very straight forward link on automotive troubleshooting. It should help.

http://www.aa1car.com/library/tselec.htm

You may have a short to power, a short to ground, or a short to another loaded circuit or some combination. It can be intermittant which is hard to duplicate. You can check the wiring without load by using an ohm meter to check resistance and continuity or you can test the loaded circuits with a voltmeter (volt drop). But nothing will replace your on site detective work.

Just as an example, I spent two or three days (off and on) tracing a problem with my brand new body harness (no power to the solenoid). It tuned out to be a main plug connection between the fuse box and the harness extension. I had to check each hole in the plug and finally saw that the connectors were not articulating when put together. I verified that by doing a continuity check across the plug. So yours could be that hard to find. I hope not.

Also, as mentioned above make sure you have anything attached to you ignition switch like fans and headlights, make sure you have an installed relay. I have two high amp fans with 10 ga purple wire but the trigger wires from the ignition are very tiny like maybe 20 ga and an 8 ga running to the battery.

WEK.

[mike w]

Thanks for all the advice. Yes I was driving at night with the lights and fan on. Since i did not build the car i am not sure if there are relays on the lights and fan. I think that I will try driving the car without these items on and see if the wires get hot. If they don't then I will trace out the fan and headlight circuit to see if relays are installed. If not, then I know what i need to do. I will keep you posted as to my findings.

[mike w]

I drove the car during the day with the lights and fan off. The wires did not get hot. Traced out the wiring to the headlights and fan and did not find any relays installed. I will install the relays before using it again. Thanks for all the advice.

[skullandbones]

Everybody loves a story with a happy ending! Glad you were able to diagnose your problem without anything bad happening. Good luck. WEK.