https://goo.gl/images/2yqz3C
https://www.naxja.org/forum/showthread.php?t=1106736

I've found this diagram, his thread doesn't say vehicle year, but on his profile year it's a 99.

does this help?

 

Go to http://cruiser54.com/?page_id=365
There you will find the 99 XJ FSM as a downloadable PDF (or zip of several PDF's).

 

downloaded, how do we proceed?

 

Hopefully Jordan will jump in here at some point - he's very knowledgeable with this testing.

The other option is to open up those FSM files and see if you can find the test procedure. There are many detailed test procedures in the FSM if you've looked through it and since they're obviously specific to the 98 XJ, you know it's "right". The FSM is also pretty good about warnings so you don't screw things up royally.

 

Using your FSM wiring diagram you should be able to identify the two wires that run through the connector to the ignition coil. With a test lamp connected to ground (battery negative), you should be able to confirm that the 12v feed is present with key on and while cranking. This is the 12v power that comes from the ASD relay. It may pulse a little while cranking - due to the amp draw created by the starter. But the pulsing should be subtle. The other wire is the wire coming from the PCM that provides the pulsing ground - when this pulses (opens the circuit) the coil produces a high voltage spike that ultimately goes to the spark plugs. Using the same test lamp, connected the same way this wire should pulse quite obviously during cranking (and while running).

You will likely have to back probe the connector with test pins in order to put the lamp on those wires with the ignition coil connected. (look up automotive backprobing if unfamiliar with the term).

Remember, at the end of the day, what you are trying to confirm is that the ASD relay is closing and provider 12v feed to ignition coil. And also that the PCM is pulsing the ignition coil to produce spark. I think you'll find that neither of these two things is happening because the PCM is not happy with the conditions.

You can also search the web for things like "diagnose ignition coil with test lamp". Here is one of the results (though I can't get audio here, so I can't judge its quality - but it is from ScannerDanner and most of his content is really sharp):

 

Oh, just for fun if you have a minute. I refer to my ECU....The later then 90 would be a Power Control Module, PCM. The Post 90 probably uses similar circuits, but they look different.. Check this out>

 

do you know anywhere I can download the powertrain diagnostics manual? Like how cruiser has it?

 

She running now, however I have two codes.

P0122 TPS circuit A low voltage
P0171 system too lean bank 1

 

While testing the tps, On 20v dc I'm getting .71v resting/idle, 3.90v at wide open throttle. It needs to be higher than .26 and lower than 4.49v so it seems good.

where else should I check for these codes?

 

I think you have a cluster of wires that ground at or near the dipstick mount. Very crucial for everything. A bit of a booger, but trying to trouble shoot without knowing those are clean and tight can be dicey!

 

I cleaned that area yesterday pulled the ring terminals and cleaned those to. Made sure the block was clean.

I tested all TPS that this thread showes:
2000 Cherokee 4.0L P0171 Code - NAXJA Forums -::- North American XJ Association
https://www.naxja.org/forum/showthread.php?t=1121271

do I test the grounds by feeding a probe to the ground on the battery and one on the wire in question?
Also what ohm setting should I be in, or just listen for tone?
if a ground is poor ANYWHERE, can I simply add a wire to the battery negaitive?

 

yes you can test grounds like that with the ohmeter set to the lowest scale.

If you can identify any bad wire, find out why, and fix it, rather than add a wire to battery, which may or may not fix the issue

If your truck runs perfectly, you possibly fixed it already, if it was a poor ground

from my readings on this forum, if there is ANY doubt on the TPS, replacing it has fixed various problems

 

Not sure if I should start a new specific thread on this :
I wouldnt say runs perfectly. It starts but starts sputtering once it's warmed up.
p0122 is there regardless, p0171 shows once it's up to normal operating temp. The jeep sounds like it's going to die. Fuel pressure is good while running/ not running, 49 psi,and it does not bleed down nor fall when accelerating.

what is recommended to test next?

 

As you have TPS code, I would check its the wiring & connectors, then replace it

the other code could be quite a few things, including vacuum leak, or bad o2 sensor...or related to tps even

have you downloaded the FSM?, it has a pretty good fault finding tree

 

someone on here sent me a link for it, I've been running through it but it's kind of incomplete, much refers to to drive train manual.
TPS checks good by all multi meter testing.
I need to check map sensor and learn how to check the 02 sensor and for vacuum leaks.