Reverse light, Neutral starter ground, and Horn relay problems

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    Author Topic: Reverse light, Neutral starter ground, and Horn relay problems  (Read 2028 times)

    Offline chargerdon

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    Reverse light, Neutral starter ground, and Horn relay problems
    « on: September 21, 2016 - 06:53:27 PM »
    Hi guys a little help please.  I'm restoring a 74 Challenger which sat for many years and I do not know its history.   When I purchased it the 318 had been taken out and had a bad block.   So, the owner I bought the car from purchased a rebuilt 360 but hadn't installed it.  The wiring harnesses for the engine compartment had all been removed by previous owner.   So, this was my starting point.   I have reinstalled the harnesses and removed the dash to facilitate putting on a new dash cover and to help install a Vintage Air box.   I now have reinstalled the dash.   I now have everything working except for:

    1) Horn.    I have tested the horn itself by hooking up a battery positive lead onto the horn wire connector and it will blow.   So, horn is good. 
    If you push on the horn switch, you get a small hum from what I believe is the 30 amp circuit breaker located on the fuse block.  Looking on page 8-66 of the 1974 sevice manual it shows the horn relay plugging into the top left of the fuse block.   My fuse block does not have a relay there, and, the fuse block itself has no spade connectors in the cavities that the picture shows.   So, I do not know how to test this circuitry.     Any advice??  Where should the horn relay be?? 

    2) Park/Neutral safety ground to starter relay AND Reverse lights not working.    Found that someone had disconnected the SINGLE wire coming from the Neutral safety/reverse light switch on the 904 automatic.   No pigtail just a single disconnected wire.   So, I have ordered a connector pigtail to fit onto the neutral switch and a new neutral/reverse switch from Rock Auto.   When they come in the Neutral wire I can run to my starter relay..  (right now I can start the car in any gear...unsafe..with a ground wire directly attached) but,

    a) where does the Reverse light wire(s) go???  Looking on page 8-150 of 1974 Service Manual I can see the bulkhead 4 wire connector for pins 3-4-7-8 that 7-8 both says Back up lamp.  Why would there be two of them??   Is this where the two wires from the switch go??   I tried putting a jumper wire between the two terminals in the bulkhead, but, the reverse lights arent lighting up.
       
    b) Lastly can I replace the old neutral/reverse switch in the 904 without it leaking tranny fluid like crazy??

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    Offline lulurocks

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    Re: Reverse light, Neutral starter ground, and Horn relay problems
    « Reply #1 on: September 21, 2016 - 09:07:28 PM »
    The  thing your are calling the 30 amp breaker is the horn relay

    See link with pic:
    https://www.google.com/search?q=73+challenger+horn+relay&rlz=1C9BKJA_enUS663US663&hl=en-US&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjx0v-x4KHPAhUDMz4KHSpwB_oQ_AUICCgC&biw=1024&bih=653#imgrc=iTLJEo9NNlT4OM%3A

    You  neutral safety switch  does two things , it grounds the start relay in park and neutral. And completes the circuit for the reverse lights.

    To test the switch, remove the wiring connector. Then test for continuity between the center terminal and the transmission case. Continuity should exist only when the transmission is in PARK or NEUTRAL.

    Shift the transmission into REVERSE and test continuity at the switch outer terminals. Continuity should exist only when the transmission is in REVERSE. Continuity should not exist between the outer terminals and the case.



    So if you jump the outer two writes in the neutral safety harness the reverse lights should light.

    So the reverse wires are 2 of the 3  that run down to the safety switch.

    To change the switch:

    If you jack up the drivers side of the car and not the passenger and put it on stands , you won't leak much fluid, it rides high in the case.

    « Last Edit: September 22, 2016 - 06:15:53 AM by lulurocks »
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    Offline chargerdon

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    Re: Reverse light, Neutral starter ground, and Horn relay problems
    « Reply #2 on: September 23, 2016 - 06:43:23 AM »
    Lulurocks...thanks a bunch!!!   Got the Horn working..   I've ordered a new neutral safety switch pigtail and switch...   will see what happens when they come in and will test the switch before attempting to replace it.   
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    Offline chargerdon

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    Re: Reverse light, Neutral starter ground, and Horn relay problems
    « Reply #3 on: October 07, 2016 - 05:24:40 PM »
    Am I unlucky or is there something weird going on.    On my transmission, I had a 1 wire switch, which did give ground when Auto tranny in Park or neutral and the wire was not connected to the relay.

    So, I bought a new 3 wire pigtail and 3 pin neutral/reverse switch thru Rock Auto.   I installed it and tested..  Yep ground on the center wire when tranny in neutral or park.   However after hooking it up to the starter relay, when I try to start the car, no starter, and the other lights all seem to dim.   What the?

    Also, I tested the two outside wires and sure enough No continuity in Park or Neutral, but continuity between them when In reverse.   However, I am also getting continuity turning on the reverse lights when in drive??

    Did i get a faulty switch, or is there something messed up in the tranny ?? 
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    Offline lulurocks

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    Re: Reverse light, Neutral starter ground, and Horn relay problems
    « Reply #4 on: October 07, 2016 - 11:02:28 PM »
    Sounds like a faulty switch.  Did you bench test it with the pigtail connected  to make sure it was good before it in the car?

    Two tests to proof out the car wiring : with nss harness disconnected

    If you have ground the. G terminal on the relay will it try to start?  This will proof out the Maybe a bad wire or connection from center pin to relay

    If you have the key in the run position and you jump the two outer pins , firewall bulkhead 7,8 do the reverse lights come on.

    If you have the key on in the run position do you have 12 volts at bulkhead wire 8 , if not check fuse  5 as well


    Are your switch test results with the 3 pin pigtail connected to the switch and not connected to the car wiring. ?
    « Last Edit: October 08, 2016 - 10:17:28 AM by lulurocks »
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    Offline chargerdon

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    Re: Reverse light, Neutral starter ground, and Horn relay problems
    « Reply #5 on: October 08, 2016 - 05:05:54 PM »
    Lulurocks:

    Sounds like a faulty switch.  Did you bench test it with the pigtail connected  to make sure it was good before it in the car? NO, as i didnt think that would matter without the tranny to activate the switch.

    Two tests to proof out the car wiring : with nss harness disconnected

    If you have ground the. G terminal on the relay will it try to start?  This will proof out the Maybe a bad wire or connection from center pin to relay
    Yes, with direct ground to the G terminal on the relay, car starts... 

    If you have the key in the run position and you jump the two outer pins , firewall bulkhead 7,8 do the reverse lights come on. Yes, jumping 7 & 8 causes the reverse lights to come on when key in run. 

    If you have the key on in the run position do you have 12 volts at bulkhead wire 8 , if not check fuse  5 as well.    Yes, I have powern when key on

    Are your switch test results with the 3 pin pigtail connected to the switch and not connected to the car wiring. ?  I installed the new switch and put on the 3 wire pigtail, without connecting the three wires to the bulkhead connector or the starter relay.   I then tested the middle wire for continuity to the tranny and when in Park and Neutral had continuity.   Next I tested the two outer wires for continuity and in Park NO, in Reverse YES Neutral NO and i didn't try any further.  I then ran a wire from the middle wire to the relay.   and the two outer to posts 7 & 8 connector to bulkhead.  Now when I try to start any lights that were on (such as my aftermarket tach wired to the accessory post on the fuse block, they dim low, and no starter.      I think that it is either a bad switch...ie. continuity but not enough to carry any amperage for the starter relay...   and unfortunately, the reverse lights are on when in drive.   So either bad switch and/or simply bad adjustment on the shifter linkage.     I noticed that I cant pull the selector the whole way back to lock in 1'st..    Think Ill try to adjust the linkage and try again. 
    « Last Edit: Today at 10:17:28 AM by lulurocks »
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    Offline chargerdon

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    Re: Reverse light, Neutral starter ground, and Horn relay problems
    « Reply #6 on: October 12, 2016 - 07:31:34 AM »
    Ok, after further testing I found a dead connector on the wire I ran for the Neutral Safety ground.   Replaced the wire and now the Neutral Safety works as it should!!

    However, the reverse light is a problem.   Testing further the two outside wires for the reverse light give continuity to make the backup lights work in Reverse AND in Drive!!    I.e in
    Park no continuity
    Reverse Continuity like it should be
    Neutral No continuity
    Drive, Second, or first    continutiy turning the backup lights ON when they shouldn't be.   

    Does anyone have the correct oem part number, to make sure I have the right switch.   I.e Rock Auto lists four different switches 2 by airtek and 2 by Standard motor products ranging in price from $6 to $12.

    Looking at Advance Auto or Oreillys they both show two BWD brand switches ranging from $12 to $19.    See: http://shop.advanceautoparts.com/p/carquest-by-bwd-neutral-safety-back-up-light-switch-s290p/5971454-P    No explanation on which is correct and both shown as exact fit.   

    So either I got the WRONG switch from Rock Auto or it is defective.   Any advice here?? 
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    Offline lulurocks

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    Re: Reverse light, Neutral starter ground, and Horn relay problems
    « Reply #7 on: October 12, 2016 - 09:23:43 AM »
    Standard ns11
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    Offline chargerdon

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    Re: Reverse light, Neutral starter ground, and Horn relay problems
    « Reply #8 on: February 05, 2017 - 02:44:47 PM »
    Ok, the real problem with the neutral/reverse switch is that my 74 Challenger has had its transmission replaced.   It has a 1968 904 in it.   

    Back in the 66-early 70 models, Chrysler put the reverse light switch on the Transmission lever, and the neutral switch was just a neutral/park safety switch only.   On the 68 Valve Body the lever doesn't have the proper end on the "rooster comb" to operate the reverse light properly.   I found this out when trying to rebuild my tranny.   

    Im going to try to buy the newer (70-77) rooster comb from WIT..   See: U12991B-3
     on https://www.wittrans.com/parts?type=A904%20(30RH-32RH)&section=90_case&part=741   Hopefully they can get me one.
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