It has been almost 2 years since I started the project. The car was a 93 4cyl auto, and it now a 306 with a tremec 5spd. I did not drive the car there is no driveshaft in it. I wanted to just start the car before I got it back to 100 % in case I had to fix something else. Anyway I turned the key and heard the new fuel pump prime up. I put the clutch in to start it and nothing. The car would not turn over. I then put the key in the on position and arched the starter solenoid and it started. Turn the key off and the car shuts off. Any idea why the car wont start with the key but will turn off? I got a set of standard pedals with the neutral safety switch. I found one small grey plug that plug into just one of the plugs on the pedals. However I have read that because the car was an auto, it should start without the switch even hooked up. Any ideas? Also I have no wiring for the tremec. It is the 3550. Is the T5 the same wiring harness? And under my dash is this cable in the attached pic. I cannot remember if it is for the auto shifter or what Any suggestions? Thanks for the help.
Got my 4cyl conversion running. Have a few questions
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lancec2c30
Member
Just to rule out some of the more simple variables, is the single wire with the rubber push pin connector hooked up to the starter solenoid?
That cable looks like it went to the auto shift assembly. So it doesn't have a use anymore.
That cable looks like it went to the auto shift assembly. So it doesn't have a use anymore.
The Tremec 3550 & T5 use the same wiring. The NSS (Neutral Safety Switch) for a 5 speed car signals the computer the transmission is in neutral, and it is safe to do the engine running diagnostics. It has nothing to do with the starter circuit.
No Crank checklist for 5.0 Mustangs
Revised 09-July-2009 to reorder stuck solenoid help.
No 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 both 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 know 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 unstuck 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 .5 volts across a connection indicates a problem.
See Automotive Test Tools for help for help troubleshooting voltage drops across connections and components. .
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
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
Starter solenoid wiring 92-93 Mustang or earlier Mustang with upgraded high torque mini starter.
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.
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.
Typical start circuit...
Diagram courtesy of Tmoss & Stang&2birds
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.
No Crank checklist for 5.0 Mustangs
Revised 09-July-2009 to reorder stuck solenoid help.
No 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 both 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 know 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 unstuck 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 .5 volts across a connection indicates a problem.
See Automotive Test Tools for help for help troubleshooting voltage drops across connections and components. .
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
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
Starter solenoid wiring 92-93 Mustang or earlier Mustang with upgraded high torque mini starter.
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.
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.
Typical start circuit...
Diagram courtesy of Tmoss & Stang&2birds
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.
still wont start from the key. I put the tranny harness in and plugged it in to the neutral safety switch and plugged in the harness to the last plug in the back of the tranny which I believe is the safety switch. Still no start with the key. Gauges turn on so does the fuel pump but no crank unless I bypass it under the hood. By the way the other 2 plugs look a little different on the T-5 harness and I am trying to hook it up to my tremec 3550. and suggestions?
Chrome_Rust
Member
under the drivers side of the dash there will be a harness that will plug into the pedal assy. If memory serves me it is either a pink wire with a blue stripe or vice versa. that is the clutch interlock switch. The auto and the manual cars use the same harness it's just in the auto cars the connector has a jumper on it. The connector should be tucked up under the dash and have a wire looped from one side to the other. Make sure that is either jumpered or plugged into the clutch pedal.
here are some diagrams to help.
here are some diagrams to help.
All of the switches are plugged into the safety switch. I did some thinking and looking and heres what I came up with. When I put the car back together I used the starter from my parts car which is a 1990. I also used the one wire that goes from the starter to the solenoid. Now on the 93 cars it is a different starter and wiring. The differences are shown in the diagram above. would this make a difference and could this possibly be my problem? The 93 starter has 2 wires that run from it to the solenoid, where the 90 only has one. I should note that all of the other wires between the 2 diagrams look the same. I should also note that the netraul safety switch is plugged into the tremec 3550. The speed sensor and the reverse lights are not plugged in. The reverse lights plug in the transmission looks like it doesnt mate up to the wiring. Is this my problem?
Follow the wiring instructions in the diagrams I posted and you will find and fix the problem. Dismiss any thoughts or concerns about the Neutral Safety Switch or reverse light switch wiring. They have nothing to do with your no start problem.
The reverse lights connector is the same on the T5 and Tremec 3550, and it has nothing to do with the starter circuit. Over the Memorial Day weekend, I swapped the T5 out of my Mustang and replaced it with a Tremec 3550, so I can assure you that the wiring is a one to one fit.
The reverse lights connector is the same on the T5 and Tremec 3550, and it has nothing to do with the starter circuit. Over the Memorial Day weekend, I swapped the T5 out of my Mustang and replaced it with a Tremec 3550, so I can assure you that the wiring is a one to one fit.
I will give these diagrams a shot. I was wondering that if the car is a 93 and I used the starter and wire out of a 90 like shown above, wouldnt the car still start? Another words its a 93 but the starter is wired like a 90.
CDQICKGT
New Member
Had the same problem. Turned out the ball at the end of the NSS was stuck. But like stated above, follow the wiring and you can't go wrong!
