1999 XJ 4.0L Automatic, 4x4

No start, no turn over. Starter doesn't even click.
Batteries are charged (I have a dual battery setup), I have dash lights but turn key to start and nothing happens.
What I've tried so far:
Checked all fuses that I'm aware of. All were good. Switched relays around, no change.
Replaced starter with new one. When I bench tested the old starter if was working fine so not the problem (oh well I have a pretty clean new one now. lol)
After replacing the starter it fired right up. Thought everything was fine but next time I tried to start it, same issue. Short the contacts on the new starter and it starts up.
I tried starting in neutral in case it was the parking gear interlock thing but it will not start in park or neutral so I assume that's not the issue but could be wrong.
I replaced the electronic side of the ignition switch. No change.
I am getting power to the injecter/fuel pump circuit for about 1.5 seconds at key on which I think is the way it should be.
On key all the way to start position I am not getting power to the starter trigger wire at the starter.
What am I missing here? Pulling my hair out? Any ideas would be appreciated. Thanks.

 

Check and renew your ground wire connections. By renew, I mean to take them off, clean them and the surface they mount to and tighten them down.

 

Thanks for the suggestion. I took apart and cleaned all the ground connections engine and body. No change.
I cut out the factory trigger wire plug (at the starter) put a new connector on the wire and screwed it directly to the starter.
No change.
Anymore ideas?

 

Have you jumped the starter between the trigger and supply/hot terminals? It should at least spin the engine over with the key off and start it if the key were on.

How long has it been since it started? Were you driving when it quit or was it you went out to start and found no response?

 

You can also bypass the NSS to verify it's not the culprit. Locate the NSS connector near the firewall, passenger side (should be grey). Disconnect. On the NSS side check for continuity between pins 7 & 8 when in Park and Neutral. You can also use a jumper between pins 7 & 8 on the harness side to see if it cranks. WARNING: With the NSS bypassed, it can start in gear.

If it's the NSS, there are plenty of writeups and YT vids on cleaning it.

 

I have not tried to jump the trigger to supply terminals. Will try tomorrow.

When I replaced the starter it fired right up. I drove it around for a few minutes and turned it off. The next day I went to take it for a proper test drive and same issue as before I changed the starter. Nothing happens when key is turned to start position.

 

I did have the NSS connector apart and jumpered the 7&8 pins. No change. I did not check continuity before I did the jumper but probably should have.

 

So what I understand you have an no crank/ no start scenario. It managed to start first after replacing starter but not since that time - you have no power at the starter, however, if you now 'short' the starter terminals on the starter it fires up, is that correct? Everytime?

I'd approach this a bit more systematic;
with a few simple steps I'm positive we can narrow this down.

Do you have access to a multimeter ?

 

What happens when you try headlights and internal fan ?

If nothing happens there, it is most likely battery cables

could be ignition switch/wiring

you need a test light or multimeter to chase electrical faults

 

I do have a multimeter.

 

I have a multimeter. It started the first time after I replaced the starter. Did not start a second time. I have power on the main terminal at the starter, but am not getting any power to the trigger wire on the starter when the key is turned to start. I have a jumper wire going from the trigger wire terminal on the starter and when I touch that to the positive battery terminal it turns over and starts if the key is in the on position. Starts up multiple times. My issue is when the ignition is turned to start position I am not getting voltage to the trigger wire going to the starter.

 

Key in on position the fan and headlights work fine. Batteries and terminals are new. Can't find any issues with the cables. When I jumper the trigger wire on the starter to the battery it starts and runs fine.

 

I have a jumper wire connected to the trigger wire terminal on the starter and when I touch it to the positive post of the battery it starts every time (with the key in on position)

 

your next logical step will be to examine the voltages at the start relay and ASD relay

You will need a circuit diagram to do this

you can find them on here via search, via Google, or best bet, download the FSM from cruisers website

I made backprobes which are just sowing pins soldered to thin wire to insert into the wiring cavities which is the easiest way to go about it

sometimes the relay board is damaged underneath, bad female connection

 

Ok; so your starter and everything else involved there is working ok. It starting up everytime, rules out things 'downstream'. Although technically your NSS isn't bypassed, if it would be faulty it wouldn't allow for starting.

So now let's move upstream and see why your starter isnt getting juice through the trigger wire;

First check continuity through this cable. Its silly to overlook this but needs ruling out.
If that's good, we move further upstream to starter relay and ASD in the underhood fusebox and will do some testing there next.


PS: For one of my experiences in diagnostic gymnastics regarding an intermittent no-start scenario, have a little light reading through this thread

https://www.ausjeepoffroad.com/forum/showthread.php?t=158807