86 5.0 Fox Body No Crank Issue (fusible Link/clutch Safety Switch)

NoTreadDyl

Member
Oct 11, 2016
49
3
18
28
Hey guys, new to the group and the proud new owner of a 1986 302 GT, been on my car bucket list since I can remember, lots of plans! So here's the scoop; I traded the my 4runner for the car knowing it needed some work. Drove it for a few days before I went to go out and she wouldn't crank, nothing.

Pulled out the multi-meter, battery is good, grounds are good, starter itself is good. The car has a fairly new solenoid by the looks of it, checked it again by jumping battery lead terminal of the solenoid to the ignition switch wire screw on the top and she turned over right away so solenoid and starter are fine. Fuses in fuse box are good. Inertia switch reset. Changed ignition switch, it produces 12 volts at the power wire on the ignition switch end (steering column) but no voltage from the ignition switch wire at the end with the rubber boot that goes onto the solenoid.

So I am thinking it is either the clutch safety switch or a fried fusible link. Onto the questions!

1) Does anyone think these last 2 possibilities are most probable or am I missing something?

2) I tried to find the clutch switch and couldn't actually locate it, is it not on the clutch petal itself or is it possible someone by-passed it? I looked up what it looks like and do not see it anywhere.

3) Does anyone know which fusible link is for the ignition wire? The schematic for the solenoid wiring is a little different than what I am seeing. The schematic shows a 10 gauge yellow wire that runs from the solenoid to the ignition switch and says it has a fusible link. However, I do not see this wire, the only yellow wire from my solenoid comes out of a fusible link that is connected to a green wire that is connected to the solenoid which is also shown in the schematic and is apparently not for the ignition wire. So it appears as thou the wire I am looking for is not there or is coming out of something different than the schematic.

My next question in regards to the fusible link is this; the fusible links I will likely change are original and say "20 gauge fusible link", my local parts places carry 18 gauge as their smallest fusible link, could I use this or should I wait it out and order 20 gauge?

4) Lastly, I started my car by jumping the solenoid a couple times to get it into the driveway to work on her, but yesterday she would crank when jumping the solenoid but would no longer turn over. Is it safe to assume this is just coincidence and bad timing? I checked coil and its good, fuel pressure is a go, so maybe ignition module? Or is there some possible link between the no crank and now no start?

I know its a mouthful but hoping I have provided enough clues that some of you experienced guys will be able to chime in to confirm I am on the right track or let me know if I have missed anything!

Thanks in advance for any input or advice! Cheers!
 
  • Like
Reactions: FoxtrotTangoWhiskey
  • Sponsors(?)


Boosted92LX

It's only an inch or two. What's the big deal?
SN Certified Technician
Dec 19, 2010
6,064
4,472
214
Hey guys, new to the group and the proud new owner of a 1986 302 GT, been on my car bucket list since I can remember, lots of plans! So here's the scoop; I traded the my 4runner for the car knowing it needed some work. Drove it for a few days before I went to go out and she wouldn't crank, nothing.

Pulled out the multi-meter, battery is good, grounds are good, starter itself is good. The car has a fairly new solenoid by the looks of it, checked it again by jumping battery lead terminal of the solenoid to the ignition switch wire screw on the top and she turned over right away so solenoid and starter are fine. Fuses in fuse box are good. Inertia switch reset. Changed ignition switch, it produces 12 volts at the power wire on the ignition switch end (steering column) but no voltage from the ignition switch wire at the end with the rubber boot that goes onto the solenoid.

So I am thinking it is either the clutch safety switch or a fried fusible link. Onto the questions!

1) Does anyone think these last 2 possibilities are most probable or am I missing something?

2) I tried to find the clutch switch and couldn't actually locate it, is it not on the clutch petal itself or is it possible someone by-passed it? I looked up what it looks like and do not see it anywhere.

3) Does anyone know which fusible link is for the ignition wire? The schematic for the solenoid wiring is a little different than what I am seeing. The schematic shows a 10 gauge yellow wire that runs from the solenoid to the ignition switch and says it has a fusible link. However, I do not see this wire, the only yellow wire from my solenoid comes out of a fusible link that is connected to a green wire that is connected to the solenoid which is also shown in the schematic and is apparently not for the ignition wire. So it appears as thou the wire I am looking for is not there or is coming out of something different than the schematic.

My next question in regards to the fusible link is this; the fusible links I will likely change are original and say "20 gauge fusible link", my local parts places carry 18 gauge as their smallest fusible link, could I use this or should I wait it out and order 20 gauge?

4) Lastly, I started my car by jumping the solenoid a couple times to get it into the driveway to work on her, but yesterday she would crank when jumping the solenoid but would no longer turn over. Is it safe to assume this is just coincidence and bad timing? I checked coil and its good, fuel pressure is a go, so maybe ignition module? Or is there some possible link between the no crank and now no start?

I know its a mouthful but hoping I have provided enough clues that some of you experienced guys will be able to chime in to confirm I am on the right track or let me know if I have missed anything!

Thanks in advance for any input or advice! Cheers!
I had a similar problem with my son's car two weeks ago. The same harness is used for auto and 5spd cars, but the 5spd car has a jumper on the neutral safety switch plug for the auto, due to no switch being there. The jumper had come out, andshe didnt start..
 
  • Like
Reactions: FoxtrotTangoWhiskey

NoTreadDyl

Member
Oct 11, 2016
49
3
18
28
I had a similar problem with my son's car two weeks ago. The same harness is used for auto and 5spd cars, but the 5spd car has a jumper on the neutral safety switch plug for the auto, due to no switch being there. The jumper had come out, andshe didnt start..
Good morning Boosted, any chance of snagging a photo of said harness and jumper? Or are you able to describe where it is or what the neutral safety switch plug looks like? Would be awesome if that's all it was!
Thanks for the input!
 

Dart68

Member
Jun 6, 2016
87
22
18
57
Hey guys, new to the group and the proud new owner of a 1986 302 GT, been on my car bucket list since I can remember, lots of plans! So here's the scoop; I traded the my 4runner for the car knowing it needed some work. Drove it for a few days before I went to go out and she wouldn't crank, nothing.

Pulled out the multi-meter, battery is good, grounds are good, starter itself is good. The car has a fairly new solenoid by the looks of it, checked it again by jumping battery lead terminal of the solenoid to the ignition switch wire screw on the top and she turned over right away so solenoid and starter are fine. Fuses in fuse box are good. Inertia switch reset. Changed ignition switch, it produces 12 volts at the power wire on the ignition switch end (steering column) but no voltage from the ignition switch wire at the end with the rubber boot that goes onto the solenoid.

So I am thinking it is either the clutch safety switch or a fried fusible link. Onto the questions!

1) Does anyone think these last 2 possibilities are most probable or am I missing something?

2) I tried to find the clutch switch and couldn't actually locate it, is it not on the clutch petal itself or is it possible someone by-passed it? I looked up what it looks like and do not see it anywhere.

3) Does anyone know which fusible link is for the ignition wire? The schematic for the solenoid wiring is a little different than what I am seeing. The schematic shows a 10 gauge yellow wire that runs from the solenoid to the ignition switch and says it has a fusible link. However, I do not see this wire, the only yellow wire from my solenoid comes out of a fusible link that is connected to a green wire that is connected to the solenoid which is also shown in the schematic and is apparently not for the ignition wire. So it appears as thou the wire I am looking for is not there or is coming out of something different than the schematic.

My next question in regards to the fusible link is this; the fusible links I will likely change are original and say "20 gauge fusible link", my local parts places carry 18 gauge as their smallest fusible link, could I use this or should I wait it out and order 20 gauge?

4) Lastly, I started my car by jumping the solenoid a couple times to get it into the driveway to work on her, but yesterday she would crank when jumping the solenoid but would no longer turn over. Is it safe to assume this is just coincidence and bad timing? I checked coil and its good, fuel pressure is a go, so maybe ignition module? Or is there some possible link between the no crank and now no start?

I know its a mouthful but hoping I have provided enough clues that some of you experienced guys will be able to chime in to confirm I am on the right track or let me know if I have missed anything!

Thanks in advance for any input or advice! Cheers!
Here's something to check. My brake lights didn't work. After tracing the wiring I found that the wire going to the brake light switch had broken in not one but two places INTERNALLY. There were no visible external signs of the break in the wire.

Check along the wire to see if there is a break somewhere that isn't visible.
 
  • Like
Reactions: FoxtrotTangoWhiskey

Moosee1955

Active Member
Sep 30, 2016
267
55
38
64
If you've got power up to the ignition switch, but not to the trigger wire going to solenoid, yes it can be the clutch interrupt switch. Don't quote me on this, but I thought it is on the tranny. Crawl under the car and look. If it's a two wire switch, pull plug touch both wires together. Try key if switch is bad car will start. Easy cheating way call dealer, parts guy can tell you where it attaches. The other test is make sure trigger wire going to solenoid has continuity, no breaks in wire. Also check grounds, especially one coming off of ignition switch. I used to have an 86 gt years back. Sorry I don't anymore, or I'd be able to help more. As far as fusible links, if it's not burnt, leave it alone. 18 gauge is safe. If a short circuit it would trip quicker. Sounds like you need a dealer DVD or book on your vehicle. Their available online or you can call Helms publishing. Best schematics. Your local library has repair books for free. Make copies of pages you need.


Sent from my iPhone using Tapatalk
 

Moosee1955

Active Member
Sep 30, 2016
267
55
38
64
Just looked up your clutch safety switch online. It has a plug that goes in the middle. It has a plastic round ring, that a pin goes through. Just from looking at it it go's around clutch pedal or somewhere near there. Check for a loose plug tucked above steering column. It's multiple wire, so jumping it will require figuring out what wires do what. Hope that helps.


Sent from my iPhone using Tapatalk
 

Boosted92LX

It's only an inch or two. What's the big deal?
SN Certified Technician
Dec 19, 2010
6,064
4,472
214
Good morning Boosted, any chance of snagging a photo of said harness and jumper? Or are you able to describe where it is or what the neutral safety switch plug looks like? Would be awesome if that's all it was!
Thanks for the input!
It is a round plug with four pins that hangs down from the floor pan onbthe driver side of the trans. If the jumper isn't there, just jumper the red and white/pink wire. I used a female spade connector. It slips over the two pins perfectly, and then just taped it all up.
 

Boosted92LX

It's only an inch or two. What's the big deal?
SN Certified Technician
Dec 19, 2010
6,064
4,472
214
Good morning Boosted, any chance of snagging a photo of said harness and jumper? Or are you able to describe where it is or what the neutral safety switch plug looks like? Would be awesome if that's all it was!
Thanks for the input!
Keep in mind this circuit travels from the ign switch, to the neutral safety switch/jumper, from there to the clutch safety switch, then to the starter relay on the inner fender. It could be the ign switch, jumper, or clutch switch.
 

Moosee1955

Active Member
Sep 30, 2016
267
55
38
64
Hey boosted, what was the switch I was looking at online? It looked like it had two separate square plugs, and a round plastic piece that looked like it went around a pin of some sort. What does his clutch switch that your talking about hook up to? The clutch pedal under car? Can the switch be jumped?


Sent from my iPhone using Tapatalk
 

Moosee1955

Active Member
Sep 30, 2016
267
55
38
64
Like I mentioned earlier, your going to need a schematic, ford ones are best.


Sent from my iPhone using Tapatalk
 

LiquidStangs

Well-Known Member
Dec 13, 2015
182
211
63
49
Indianapolis metro area
BTW, should have mentioned: the big black bar in the middle of the second pic is the clutch pedal.

Also, if stuff looks wrong around the brake pedal, that's because of my ongoing attempt to fix my brakes. If wiring stuff looks wrong... well, thank the Previous Owner for that.

EDIT: Also forgot to mention that mine is an '89. LMR sez that my switch went back all the way to '86.
 
  • Like
Reactions: Boosted92LX

Moosee1955

Active Member
Sep 30, 2016
267
55
38
64
That's the switch I saw online. Did you just swap it out, or did you jump the wires first?


Sent from my iPhone using Tapatalk
 

LiquidStangs

Well-Known Member
Dec 13, 2015
182
211
63
49
Indianapolis metro area
If I remember correctly, I jumped the wires in the harness, but only to verify the fix before buying a new one.

The plastic rod is supposed to click-to-adjust, much like the stock quadrant, but mine had totally stripped out.
 

Moosee1955

Active Member
Sep 30, 2016
267
55
38
64
That's what I thought. He'll need to get a wiring diagram and jump his clutch switch and neutral switch. If neutral switch is a two wire , a lot are, jump the 2 leads together. That ones a no brainer.


Sent from my iPhone using Tapatalk
 

jrichker

StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
27,084
2,626
224
73
Dublin GA
Diagrams are in here...


No Crank checklist for 5.0 Mustangs

Revised 24-Oct-2013 to update voltage drop figures.

No crank, slow crank and stuck starter solenoid problems have the same root causes – low battery voltage and poor connections. For that reason, they are grouped together.
Use the same initial group of tests to find the root cause of slow crank, no crank and stuck solenoid problems.

Since some of the tests will bypass the safety interlocks, make sure that the car is in neutral and the parking brake is set. Becoming a pancake isn’t part of the repair process…


1.) Will the car start if it is jumped? Then clean battery terminals and check battery for low charge and dead cells. A good battery will measure 12-13 volts at full charge with the ignition switch in the Run position but without the engine running.
A voltmeter placed across the battery terminals should show a minimum of 9.5-10 volts when the ignition switch is turned to the Start position and the starter engages or tries to engage. Less than this will result in a clicking solenoid, or slow cranking (if it cranks at all) or a starter solenoid that sticks and welds the contacts together.

Most auto parts stores will check your battery for free. It does not have to be installed in the car to have it checked; you can carry it with you to the auto parts store.

The battery posts and inside of the battery post terminals should be scraped clean with a knife or battery post cleaner tool. This little trick will fix a surprising number of no start problems.

The clamp on with 2 bolts battery terminal ends are a known problem causer. Any place you see green on a copper wire is corrosion. Corrosion gets in the clamped joint and works its way up the wire under the insulation. Corroded connections do not conduct electricity well. Avoid them like the plague...

If the starter solenoid welds the contacts, then the starter will attempt to run anytime there is power in the battery. The cables and solenoid will get very hot, and may even start smoking. The temporary fix for a welded starter solenoid is to disconnect the battery and smack the back of the solenoid housing a sharp blow with a hammer. This may cause the contacts to unstick and work normally for a while.


A voltmeter is handy if you are familiar with how to use it to find bad connections. Measure the voltage drop across a connection while trying to start the car: more than .25 volts across a connection indicates a problem. The voltage drop tests need to be done while cranking the engine. It's the current flowing through a connection or wire that causes the voltage drop.

See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help for help troubleshooting voltage drops across connections and components. .

attachment.php?attachmentid=64167&stc=1&d=1286329941.gif


Voltage drops should not exceed the following:
200 mV Wire or cable
300 mV Switch or solenoid
100 mV Ground
0.0V Connections
A voltage drop lower that spec is always acceptable.

2.) Check the battery to engine block ground down near the oil filter, and the ground behind the engine to the firewall. All grounds should be clean and shiny. Use some sandpaper to clean them up.

3.) Jump the big terminals on the starter solenoid next to the battery with a screwdriver - watch out for the sparks! If the engine cranks, the starter and power wiring is good. The starter relay is also known as a starter solenoid.

The rest of the tech note only concerns no crank problems. If your problem was a stuck solenoid, go back to step 1.

4.) Then pull the small push on connector (small red/blue wire) off the starter solenoid (Looks like it is stuck on a screw). Then jump between the screw and the terminal that is connected to the battery. If it cranks, the relay is good and your problem is in the rest of the circuit.

5.) Remember to check the ignition switch, neutral safety switch on auto trans and the clutch safety switch on manual trans cars. If they are good, then you have wiring problems.

Typical start circuit...
Diagram courtesy of Tmoss & Stang&2birds
attachment.php?attachmentid=21328&d=1080916057.gif



6.) Pull the starter and take it to AutoZone or Pep Boys and have them test it. Starter fails test, then replace it. If you got this far, the starter is probably bad.


Starter solenoid wiring for 86-91 Mustang
attachment.php?attachmentid=52294&stc=1&d=1192414749.gif



Starter solenoid wiring 92-93 Mustang or earlier Mustang with upgraded high torque mini starter.
attachment.php?attachmentid=53216&stc=1&d=1201020653.gif


Electrical checks for the switches and starter solenoid

Remove the small red/blue wire from the starter solenoid. Use a screwdriver to bridge the connection from the battery positive connection on the starter solenoid to the small screw where the red/blue wire was connected. The starter should crank the engine. If it does not, the starter solenoid is defective or the battery lacks sufficient charge to crank the engine.

If the starter does crank the engine, the problem is in the clutch safety circuit (5 speed) or Neutral Sense Switch (auto trans) or ignition switch.


See the Typical start circuit diagram above for wiring information for troubleshooting.

You will need a voltmeter or test lamp for the rest of the checks. Connect one lead of the voltmeter or test lamp to ground. The other lead will connect to the item under test.
Look for 12 volts on the white/pink wire when the ignition switch is turned to the Start position. Check the ignition switch first.
No 12 volts, replace the ignition switch.

The next step will require you to push the clutch pedal to the floor (5 speed) or put the transmission in neutral (auto trans) while the ignition switch is turned to the Start position.
Good 12 volts, check the clutch safety switch (5 speed) or Neutral Sense Switch (auto trans) for good 12 volts on both sides of the switches. No 12 volts on both sides of the switch and the switches are defective or out of adjustment. Check the wiring for bad connections while you are at it.
 

Moosee1955

Active Member
Sep 30, 2016
267
55
38
64
Thanks for forwarding the flow chart. I only have an I phone, and have to wing it. Hopefully he'll figure out his problem. The fact he doesn't have 12 volt to wire from ignition switch to starter solenoid narrows down a few items, assuming that wire is good. Thanks again. I used to have an 86 before it was stolen. Kind of soft spot for car.


Sent from my iPhone using Tapatalk
 

NoTreadDyl

Member
Oct 11, 2016
49
3
18
28
Thanks a lot guys, this is my first time actually posting in a forum. I usually find the answers from the same questions others already asked. That being said I have already acquired the schematics and the no crank checklist from other posts, I like to do my best before getting people to invest their time into my problem!

It is narrowed down quite a bit, the ignition switch has been replaced and has 12 volts. It has to be in the clutch safety circuit, or the wiring in between. That circuit seams to be a somewhat confusing topic online thou, different people describing different switches in different locations.

Boosted, you mentioned there is a clutch safety switch and a neutral safety switch, perhaps people describing one or the other is whats causing the confusion. Is one of the switches under the car at the tranny as described by multiple people and the other is near the pedal as described by others?Also you mentioned jumping the white/pink wire and the red/green wire, do you mean to do this at the ignition switch? It is soo freaking hard to access the wiring harness and such under the steering column! I see a round plug under the car hanging near the tranny but the car is an inch of the ground, can't even get my ramps under it an no jack so going to try and located the switch near the column and get a jack in the next day or two to get under her.

Jrichker, thanks so much for providing the checklist for so many people, I was able to narrow down the problem to where it is now basically from that checklist, before I posted anything myself. Very helpful and very much appreciated! And thanks to everyone else for the responses, great first experience with this forum!
 

NoTreadDyl

Member
Oct 11, 2016
49
3
18
28
My clutch safety switch went out not too long ago. For some reason, I still have the old one:

IMG_20161012_184626.jpg


And here's the new one, in the car. The wiring harness with light blue and yellow wires is plugged into it.

IMG_20161012_184745.jpg
I swear that is not in my car haha, I have been in there and seen right up to the top of the petal and can't see it. I used a flashlight and just took another look and saw 2 light blue/yellow wires going into a clip that had one on the other side, but no switch! I wonder if some of these cars had it there like yours and some have it under the car next to the tranny like some people are describing? Or is there two different switches, same car haha! Going to use these photos and look again tomorrow one more time, but almost certain I don't have it, perhaps someone by passed it entirely already? Thanks for the photos and your time, cheers!
 

Moosee1955

Active Member
Sep 30, 2016
267
55
38
64
The neutral switch is supposed to be on top of transmission drivers side, from what I've read. I haven't owned mine since 2000, that's when it was stolen/ stripped. It is getting close to Halloween, maybe a ghost is hiding your clutch switch.! Boooo!


Sent from my iPhone using Tapatalk
 
  • Like
Reactions: NoTreadDyl