Hi all. I hope someone can help me. My jeep cherokee randomly didn't start one day after stopping at a gas station. I threw it in neutral and it started right up. I thought this could be issues with the NSS because I was having intermittent "no reverse lights" issues, but never any starting issues. Well the next time I went to start the jeep, it wouldn't start in park or neutral. I disconnected the NSS at the plug and tried the paperclip trick, but nada. I unhooked the NSS from the trans and cleaned it out, reassembled with dielectric grease, made sure the springs were well cleaned and it looked good as new.

Slapped it back on the trans and plugged it in, car still wont start. No click, no crank. (Reverse lights work). I tested the ignition switch by doing the heater fan test (turn heater on and turn key to start position, heater should turn off) and that seems fine, however the car has displayed ignition switch issues in the past (dash, windshield wipers, radio, heater all turned off while driving multiple days of the week.) Currently car has all lights and everything, reverse lights work and the battery gauge on the dash reads 12V.

I can only imagine now that its the starter or starter switch. I hit the starter with a wrench but it still didn't start. Anyone have any ideas? I feel like she's just trying to spite me since this happened the day after I listed it for sale on facebook.

 

Without a meter, it's a guess

 

How old is the starter? How do the battery connections look?

Yes, it could be the starter or the starter solenoid (also on the starter), or even the ignition switch. The starter solenoid is where the positive battery cable goes. When activated (key turned on) a plunger is magnetically pulled into the end of the solenoid which touches other contacts (battery and starter motor) and closes the circuit (engages the starter motor). At the instance just before the copper disc (on the plunger inside the solenoid) meets the battery and starter motor contacts, there is a small amount of arcing which occurs. Over many years, the copper disc and/or the two other contacts become pitted and slowly erode away. After many years, they can wear to the point where there is no more (or very little) copper material left to close that circuit. When that occurs, the starter will either start intermittently for a while, or not at all depending on whats left of the contacts.

Also, the brushes inside the starter that transfer electricity to the starter motor itself also wear. After many many years they can simply wear down to a nub. Meaning, there's just no more carbon brush material left to transfer power to the starter motor. There can be a period when the vehicle might start intermittently if the brushes 'happen' to still make contact ..but may not start if they don't. Other things that can go wrong include a brush wire corroding or breaking off, or other internal starter issues.

Start switches can also fail. Usually you'll notice this if/when you turn the key a number of times and it happens to start somewhat randomly.

You can buy new starter solenoids ...and even starter brushes kits. These are the two most common failure points. Ebay is a good place for those. The Mitsubishi gear starter is one of the most popular starters ever. They used them on lots of vehicles. They're pretty inexpensive too. I often rebuild my starters & alternators because they're fun and educational to do. But if you're not into component R&R, remove the starter, bench-test it ...and/or replace if it's not operating (parts stores will test for free). You can pop off the back cover and have a quick look at the brushes. You'll know instantly if they're worn out. But getting the cover back on can be a trick too.

 

You can quickly test the starter by using a small jumper. The small terminal on the solenoid gets power when they key is turned to START through the starter relay. This energizes the solenoid and cranks the starter, If you jump the small terminal on the starter to the large battery terminal next to it (coming from the battery), the starter should crank. Make sure you don't jump to the other large terminal. Leave the key off to prevent it from actually starting, Repeat this several times. If it cranks consistently, your problem lies upstream.

If you don't have it, you can find the FSM at https://cruiser54.com/?page_id=365

 

I would suggest checking your battery terminals, battery cables and grounding points. Make sure they are clean and tight, meaning take them apart, clean them(wire brush, steel wool, Emory paper) to bare and shiny metal and reassemble. And do not bother with dielectric grease on these components. Battery cable also can corrode under the insulation and you should check for that.
And if that doesn't work, take your battery in to an auto parts store and have it tested.

 

...and without data, all you have is an opinion, lol

 

Alright, so I guess I can rule out the starter and starter solenoid. I took the cap off the starter relay to see if anything was wrong, and when I touched the coil of the starter relay the starter started turning over. I went into the cab and turned the key to run which resulted in nothing happening, then when I touched the starter relay again, the starter cranked and the engine turned over immediately. So at this point, I think its down to the starter relay being bad or a fuse nearby, maybe I'm creating a ground when I touch the coil, I certainly dont feel any jolt passing through my hand. Are there any relays/fuses I should swap to troubleshoot before swapping out the ignition switch?

 

You can try swapping the relay for any other like it in the PDC. Just bear in mind that the other system may not function if the relay is bad, but you'll have determined it's the relay. Check Fuse 6 (60a) & 7 (40a) in the PDC.

Here's the pinout for the starter relay.



So pin 27 should have 12v. If not, check fuse 7.

Pin 26 should have 12v only with the key in START, If not, check fuse 6. If fuse 6 good, could be ignition sw.

Pin 29 is the wire that runs to the small terminal on the starter, With the relay out, you can check for continuity.

Pin 30 runs to the Neutral safety switch. I would try the "paperclip" bypass just to be sure. Make sure you jump the main harness side, not the switch side.

 

Thanks for your help. I swapped the relays and still no start. I then bought a new ignition switch and replaced but still no start. My only guess now is a bad ground somewhere? Anyone know which ground from the ignition would prevent the car from starting? When I turn the key, the fuel pump primes but no ignition.

 

I would download this, which is for a 1995 model, and go to page 337, and methodically work through the tests

I presume you have a multimeter and know how to use it, or you cannot diagnose the problem

A number of obvious faults need checks, such as whether the starter relay has 12V, whether it has earth, whether it receives a 12V signal from the ignition key wire

I am not certain how the starter relay receives its earth, it may be via the ASD relay or PCM. That information is in the Service manual

a damaged relay board female terminal is not unknown, nor a bad wire. A relay can also be removed and tested

Its almost always quicker to systematically fault find electrical problems than change parts

one can use a thin wire, or a thin wire with a pin attached to act as a back probe

" Powertrain Diagnostic Procedures Manual" - Jeep Cherokee Forum

 

The starter relay grounds through the NSS so Park or Neutral complete the path to energize the starter relay with the key in START.

Sounds like it's time to break out the multimeter and start checking voltages and continuity.

As AWG suggests, also make sure the pins/terminals inside the connectors are not corroded or pushed out.

 

There is very detailed instructions in that free manual I linked to diagnose the starter relay situation.

It would even be able to be easily done with a test light

 

I appreciate the help guys, I really do. I didn't have a multi meter on hand nor have I ever used one. I purchased one after todays events because I'm at the end of my rope. I disconnected 4 of the ground in the engine bay and cleaned them thoroughly. These 4 would be the battery negative post to fender, the oil dipstick one and the 2 roughly a foot infront of that one towards the front of the motor under the a/c compressor. I expected the car to start after this because the 3 connected under the oil dipstick area were especially dirty. To my surprise, the car didn't start. I then swapped the ignition cylinder and with a new set of keys, the car still doesn't start.

To summarize, what all I've done and under what conditions the car starts, here's a list.

Cleaned and disconnected the NSS, reconstructed with dielectric grease. (note: the car did not start via paperclip method before or after this step)
Swapped the ignition switch with a new one (note: the contacts on the large pin connector on the furthest right side were greenish tinted. Sprayed the inside of the clip with electrical contact cleaner and let dry)
Swapped the ignition cylinder with a new one (note: no change has occurred. Car still starts with key in run position and starter relay pressed.)

To get the car to start-
key inserted into run position (note: fuel pump primes, electrical all turns on when key is inserted, no audible noise other than that.)
under hood, I press on the starter relay metal contact circled in the picture below. This makes the starter crank and if the key is not inserted or not in the run position, it will crank as long as I have the contact pressed against the other contact.
After 1 second of cranking, the Jeep will start.


Note: This isn't a picture of my fuse box, this is another forum member's that had a similar problem. His thread can be found here. https://www.cherokeeforum.com/f67/pu...tarted-113829/

If anyone has any advice on using the multimeter that I purchased today, that would be great. I will be heading out tomorrow to see what information I can gather. Any key voltage readings to make note of or where to start would be appreciated. I'm a novice when it comes to electrical work so if any directions can be simplified, that would be great.

 

there is absolutely clear instructions on page 342-345 of the manual I linked to perform these tests

Youtube will give you enough to learn how to operate a multimeter

afaic, you have proved you have 12V running thru the relay by pressing the contacts and it starts

Remove the relay

You should check whether 12V is on slot 26 ONLY when key is turned to start

If NO, you have wiring/connector/ignition key (or some other issue)

If Yes, check whether there is less than 5 Ohms between slot 30 and Battery negative terminal

If Yes, check the resistance between pin 26 and pin 30 on the relay. It should be less than 100 Ohms

If it is NOT, the switching coil on the relay has probably failed

It helps a lot to identify which pin/slot is which. I think this is in the FSM, sometimes printed on the relay case

Report your findings

I recently had to replace a bad relay on my son's vehicle. Had to Google for ages to even find out where the relay was located in the vehicle

It was a weird relay, and I had to figure out what pins did what, got another one on Ebay, in the meanwhile, he had to push the contacts in manually

 

Thanks again, AWG. I couldn't open the google doc because I am not granted access. Perhaps you could upload your copy on google drive or is there another one I can find?