Neutral Safety Switch/Clutch Safety Switch
07-14-2014, 03:20 PM
#1
Registered User
Thread Starter
Neutral Safety Switch/Clutch Safety Switch
I am in need of some clarification and guidance. I have battled my cruise control not working, as well as my reverse lights not working either. I have done some reading on these issues, and I believe that I am dealing with an issue with my neutral safety switch of some form or another. I am thinking the switch is junk, or isnt grounded properly, or needs to be jumped or something of that nature. Can someone tell me where the NSS is? A quick picture would be even better! After I am guided to the location of the switch (thanks in advanced) is there a quick way i can test it?
Also, is there a difference between the neutral safety switch and the clutch safety switch? Ive owned this truck for 4 years, had the manual trans for a year and a half, and no matter how much I learn about this rig I always feel like I need an answer to a seemingly simple question that are kind of "no brainers"
Thanks guys!
Also, is there a difference between the neutral safety switch and the clutch safety switch? Ive owned this truck for 4 years, had the manual trans for a year and a half, and no matter how much I learn about this rig I always feel like I need an answer to a seemingly simple question that are kind of "no brainers"
Thanks guys!
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JED72 (03-25-2022)
07-14-2014, 03:33 PM
#2
Registered User
Thread Starter
*additional information*
I hired a "mechanic" to swap my a518 to an NV4500. Im very dissapointed with the work quality, as many things were done incorrectly. This is the part that makes it difficult for regular trouble shooting. I have no idea what he did for wiring the transmission in.
Would the swap change the location of the neutral safety switch? Would it be on the clutch pedal or on the back of the transmission?
And as it says in my sig, 1993 W250
I hired a "mechanic" to swap my a518 to an NV4500. Im very dissapointed with the work quality, as many things were done incorrectly. This is the part that makes it difficult for regular trouble shooting. I have no idea what he did for wiring the transmission in.
Would the swap change the location of the neutral safety switch? Would it be on the clutch pedal or on the back of the transmission?
And as it says in my sig, 1993 W250
07-14-2014, 05:31 PM
#3
Cummins Guru
As far as I know it has always been on the clutch master cylinder push rod under the dash. You can jump the switch to test it just grounds start relay for the starter solenoid. Caution if you jump the switch truck will start without stepping on clutch and can start in gear. Clutch switch fig. 7
07-14-2014, 05:38 PM
#4
Registered User
that is where my 90 donor is. I think the (stock)manual transmission wiring harness reroutes the automatic neutral safety switch to the clutch switch.
07-14-2014, 09:46 PM
#5
Registered User
OK I am assuming the "mechanic" re-used your original transmission wiring harness? If so then what you need to do is find a round black plug with 3 wires running to it.
Once you locate this plug....if the "mechanic" hasn't already cut off the plug, then there will be a brown wire with a yellow tracer. Chances are he "mechanic" has just cut the wire and run it to a ground. Anyway This is your neutral safety wire. For your cruise to work properly, You will need to run this wire up to your interior and either put it on a push button, or wire it up to a brake light type switch on your clutch pedal. You need the ECM to read ground so it will start, but after the truck is running the ECM must not see that ground, or the cruise will never work.
The other two wires, are your reverse light. Just wire them up to the reverse light switch on your tranmission. With a NV4500 it should be on the drivers side on the top cover. You should have a 2 wire pig tail off the plug. Just hook the wires up and see what happens, you got a 50/50 chance of getting it right.
If you get it wrong they will just light up with out actually going into gear. If you get it right, then they will work properly.
Hopefully I explained things clear enough...if not then let me know and I will try to explain it better.
Once you locate this plug....if the "mechanic" hasn't already cut off the plug, then there will be a brown wire with a yellow tracer. Chances are he "mechanic" has just cut the wire and run it to a ground. Anyway This is your neutral safety wire. For your cruise to work properly, You will need to run this wire up to your interior and either put it on a push button, or wire it up to a brake light type switch on your clutch pedal. You need the ECM to read ground so it will start, but after the truck is running the ECM must not see that ground, or the cruise will never work.
The other two wires, are your reverse light. Just wire them up to the reverse light switch on your tranmission. With a NV4500 it should be on the drivers side on the top cover. You should have a 2 wire pig tail off the plug. Just hook the wires up and see what happens, you got a 50/50 chance of getting it right.
If you get it wrong they will just light up with out actually going into gear. If you get it right, then they will work properly.
Hopefully I explained things clear enough...if not then let me know and I will try to explain it better.
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JED72 (03-25-2022)
07-15-2014, 07:18 AM
#6
If the clutch pedal switch is not being used. Wire your neutral wire to one side. The other side take to ground. Then the truck will only start with the clutch depressed.
If he did hook the pedal switch up. Jumper the harness side plug. Then still take the neutral wire to the switch.
If he did hook the pedal switch up. Jumper the harness side plug. Then still take the neutral wire to the switch.
07-15-2014, 08:56 AM
#7
Registered User
Thread Starter
you guys are awesome.
And yes, he just cut and spliced and re-used the stock automatic harness, carelessly i might add.
I fiddled around with it last night. I believe i found the clutch safety switch. The wire had the jumper, so i wired that up. Before that, I was able to start my truck without the clutch being in. Now, clutch has to be depressed. So the good news is im making progress!
thrashingcows, that is a great explanation. Now i just have to wait for this pesky work day to be over so i can go poke around and see what i can find.
this is the jumper wire that I wired into the picture below. doing this made the clutch have to be depressed to start the truck.
This is what I determined to be the clutch safety switch.
And yes, he just cut and spliced and re-used the stock automatic harness, carelessly i might add.
I fiddled around with it last night. I believe i found the clutch safety switch. The wire had the jumper, so i wired that up. Before that, I was able to start my truck without the clutch being in. Now, clutch has to be depressed. So the good news is im making progress!
thrashingcows, that is a great explanation. Now i just have to wait for this pesky work day to be over so i can go poke around and see what i can find.
this is the jumper wire that I wired into the picture below. doing this made the clutch have to be depressed to start the truck.
This is what I determined to be the clutch safety switch.
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07-15-2014, 11:01 AM
#8
Registered User
OK I am assuming the "mechanic" re-used your original transmission wiring harness? If so then what you need to do is find a round black plug with 3 wires running to it.
Once you locate this plug....if the "mechanic" hasn't already cut off the plug, then there will be a brown wire with a yellow tracer. Chances are he "mechanic" has just cut the wire and run it to a ground. Anyway This is your neutral safety wire. For your cruise to work properly, You will need to run this wire up to your interior and either put it on a push button, or wire it up to a brake light type switch on your clutch pedal. You need the ECM to read ground so it will start, but after the truck is running the ECM must not see that ground, or the cruise will never work.
The other two wires, are your reverse light. Just wire them up to the reverse light switch on your tranmission. With a NV4500 it should be on the drivers side on the top cover. You should have a 2 wire pig tail off the plug. Just hook the wires up and see what happens, you got a 50/50 chance of getting it right.
If you get it wrong they will just light up with out actually going into gear. If you get it right, then they will work properly.
Hopefully I explained things clear enough...if not then let me know and I will try to explain it better.
Once you locate this plug....if the "mechanic" hasn't already cut off the plug, then there will be a brown wire with a yellow tracer. Chances are he "mechanic" has just cut the wire and run it to a ground. Anyway This is your neutral safety wire. For your cruise to work properly, You will need to run this wire up to your interior and either put it on a push button, or wire it up to a brake light type switch on your clutch pedal. You need the ECM to read ground so it will start, but after the truck is running the ECM must not see that ground, or the cruise will never work.
The other two wires, are your reverse light. Just wire them up to the reverse light switch on your tranmission. With a NV4500 it should be on the drivers side on the top cover. You should have a 2 wire pig tail off the plug. Just hook the wires up and see what happens, you got a 50/50 chance of getting it right.
If you get it wrong they will just light up with out actually going into gear. If you get it right, then they will work properly.
Hopefully I explained things clear enough...if not then let me know and I will try to explain it better.
07-15-2014, 01:16 PM
#10
Registered User
Thread Starter
look what i found on my lunch break 
now i need to find the other ends of the wires and hook em up!
For the time being Im gonna hook the cruise wire up to a ground and hook it up to a toggle until i have time to do it correctly. it just needs a small signal so a 3 amp switch would work, correct?
got a 530 mile tow trip this weekend with the old girl. my gauges are supposed to come in so i can have them installed by saturday morning
now i need to find the other ends of the wires and hook em up!
For the time being Im gonna hook the cruise wire up to a ground and hook it up to a toggle until i have time to do it correctly. it just needs a small signal so a 3 amp switch would work, correct?
got a 530 mile tow trip this weekend with the old girl. my gauges are supposed to come in so i can have them installed by saturday morning
07-15-2014, 06:13 PM
#11
Registered User
Since you tied into the stock clutch pedal neutral safety switch. That brown wire, with the yellow tracer, might be irrelevant now?
Will your truck start without the clutch pedal being in? I believe you stated before that it would start regardless if you were in gear, or if the clutch pedal was in or not....correct?
The two out side wires will be the reverse lights. My guess is the two snipped wires were run up to the reverse light switch. One is/was the neutral safety ground and was grounding out on the switch.
Will your truck start without the clutch pedal being in? I believe you stated before that it would start regardless if you were in gear, or if the clutch pedal was in or not....correct?
The two out side wires will be the reverse lights. My guess is the two snipped wires were run up to the reverse light switch. One is/was the neutral safety ground and was grounding out on the switch.
07-15-2014, 11:12 PM
#12
Registered User
Thread Starter
My truck used to start whenever you turned the key regardless of the clutch or if it was in gear. Now that I've ran those worse I must have the clutch on the floor to start it.
I simply got rid of the jumper wire and plugged in the wires from the switch to the connector that was jumped
I simply got rid of the jumper wire and plugged in the wires from the switch to the connector that was jumped
07-15-2014, 11:40 PM
#13
Registered User
Well then there is a good chance that the cruise might work now.
I would still find where that brown wire, with yellow tracer is run, and disconnect it and tape it up out of the way...just to be on the safe side.
Then all that's left is getting those reverse lights working.
I would still find where that brown wire, with yellow tracer is run, and disconnect it and tape it up out of the way...just to be on the safe side.
Then all that's left is getting those reverse lights working.
07-16-2014, 07:20 AM
#14
You have an auto PCM. If you leave that neutral wire grounded. You will not have cruse control. The PCM thinks you in park or neutral. So you don't need CC.
Put the jumper plug back it. Wire your neutral wire into the clutch switch. Use the second wire off the clutch switch to a ground.
A stick shift truck is wired different than a auto. The PCM has different programing between the two trans.
Put the jumper plug back it. Wire your neutral wire into the clutch switch. Use the second wire off the clutch switch to a ground.
A stick shift truck is wired different than a auto. The PCM has different programing between the two trans.
07-16-2014, 07:53 AM
#15
Registered User
Thread Starter
that makes sense Phillip. cruise didnt work when the jumper wire was in, doesnt work now. I will say i like the idea of the clutch needing to be in to start the truck though.
I didnt have any time to mess with it last night, but will have time tonight. Ill get all of that goin and see what happens. Does it matter which wire off the clutch switch gets grounded and which gets connected to the brown/yellow wire?
I didnt have any time to mess with it last night, but will have time tonight. Ill get all of that goin and see what happens. Does it matter which wire off the clutch switch gets grounded and which gets connected to the brown/yellow wire?