neutral safety switch

[SPCBruce89]

my MJ starts fine but after it runs for a bit ill shut it off to go into a store or somewhere then go to start it again and nothing. If i let it cool off it starts fine :???: so far Ive replaced everything from the battery to the starter and everything in between. all i haven't changed out is the ignition and clutch slave cylinder (if that's where the neutral safety switch is) any suggestions? cause id like to do more of this and less of this :wrench: this winter

[JeffN]

If it is a manual it won't have a neutral safety switch, I am not sure if it has a clutch switch or not.

[SPCBruce89]

it is a manual and it does need a clutch replacement that is next but i wanted to figure the starting problem out first

[jimoshel]

Sounds like the ign sw to me but it also could be the starter solenoid. Hook a remote starter button into the circuit, one lead to the bat pos and the other lead to the little terminal on the solenoid. Now when it doesn't want to start hit the remote button. If it starts then the ign sw is bad. If it still doesn't start then it's the solenoid.

[carnuck]

Does the motor spin? If not, then the switch at the top of the clutch pedal or a loose ground wire on the block (heats up from running then stops contact till it cools and contracts till it touches again)

If the motor does spin, either you are getting no fuel (fuel pump relay, pump resistor is cracked or pump is dying) or no spark/injector signal. (weak CPS, melted harness on exhaust manifold, bad coolant sensor for the computer or corrosion between the coil and ignition box under it.

[SPCBruce89]

it clicks like it wants to start then nothing. but if i let it sit for ten mins it starts fine. here is a list of what all Ive replaced

battery

starter

alternator

starter solenoid

all plugs and wires

[JeffN]

clean and tighten battery cables

[cruiser54]

Do this then:

 

Renix Ground Refreshing

 

The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.

 

The components grounding at the dipstick tube stud are:

 

Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.

 

The factory was aware of the issues with this ground point and addressed it by suggesting the following:

 

Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.

 

Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.

 

While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.

 

Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.

 

First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.

Remove the other end of the cable from the rear of the head using a 3’4” socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.

 

A suggestion regarding the braided cable:

I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18” long with a 3/8” lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.

 

A further improvement to the grounding system can be made using a #4 cable, about 10” long with 3/8” terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.

 

 

 

If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.

 

 

Revised 11-28-2011

[SPCBruce89]

I'm gonna clean all the grounds today hopefully it works fingers crossed