99 XJ 4.0L code P1698, won't stay running
 

Ok my daughter's jeep started acting up last week. She said it was bucking while driving it . The CEL was on dash,so I checked codes. I got the P1698and P0420. I'm pretty sure the P0420 is an O2 sensor issue. But the P1698 is PCM related from what I've found thus far. I erased codes and she had driven it a few more days with no issues. Then Saturday morning she tells me the jeep won't start, it's just making the clicking noise. I recently replaced the starter late last year. So I doubted a bad starter again. The jeep was stuck at a friends apartment overnight. I got to look at jeep Sunday morning. Battery was dead. I called a tow truck as I couldn't access battery to Jumpstart it due to parking on each side of jeep. Tow service jumped it with booster box. But it would only start by giving it gas. And would die immediately upon letting of the gas. So we had to push jeep back out parking space to put it up on flatbed. Tow guy said he thought it may be a bad alternator. But nonetheless, got it to house and immediately hooked up charger to battery,unhooked cables also. It took all of Sunday and today for full charge. When I got home from work this evening, I started looking at jeep. I hooked up cables and went to start it but only turns over again. Had to give it gas to start it and again , it dies immediately if letting of gas. Again a CEL ON dash and again the P1698 ..... So I start checking fuses in engine compartment in relation to ignition, fuel,etc. All were good. All fuses in passenger kick panel were good too. So I'm kind of stumped as what it may be. Is there a way to check alternator on truck or take it to parts store to be bench tested? Could it be TPS related because it will only run by giving it gas/throttle? Or is it possibly PCM is bad? Any help is greatly appreciated! Just point me in the right direction or tell me what is wrong. .... Thanks in advance!

First, you have either a bad battery or your charging system isn't keeping your battery charged. Have your battery "load tested" at any parts store. Either have your charging system tested at that same parts store, take the alternator off and have it bench tested, or do a quick and dirty test with a meter. At idle, you should see between 13.5 and 14.4 volts when measured at the battery. You gotta get your electrical system squared away before chasing the other issues, as marginal electrical can create other gremlins.

As for the P0420. Catalytic converter efficiency failure. Here's more. It's not necessarily the oxygen sensor. P1698 gets kind of difficult if it's still popping. A "search" for this code + XJ will get you lots of light reading and diagnostic procedures. Good luck!

http://engine-codes.com/p0420_jeep.html

http://www.obd-codes.com/p0420

How do I check the charging system when the jeep won't idle on its own? I guess I can take battery and alternator into parts store to be tested then.

Bump...... Anybody got anything on this issue?

99 XJ 4.0L code P1698, won't stay running
 

Did you get it tested yet? That's your first troubleshooting step. Get that done, and based on what you find out, then someone might have more ideas. Otherwise we would be sending you on a wild goose chase.

Your tps is not related to this (or shouldn't be). Your computer doesn't know what to do for some reason - it's a communication issue i.e. connection. Did you read this?

https://www.cherokeeforum.com/f2/tro...e-p1698-99973/

Also, you can remove your alternator and get it bench tested.

Here's some reading material for you, pertaining to P1698:


https://www.cherokeeforum.com/f2/p1698-200371/

Not yet. Got a storm last night so couldn't pull alternator. Will do that this evening after work if weather permits.

I will check the grounds also. The ECM connections looked good and clean, no corrosion. But where is the TCM located? I need to check that also. Thanks.

Under the dash, to the right of the steering column. You'll need to remove the trim panel and knee blocker from around the steering column to get at it.


Attachment 313887


Looks like this:



Attachment 313888

Ok so I just got back from parts store. They tested both the alternator which was good. And the battery both tested good. So with that being said,what should I begin checking next?

An FYI for you. Be aware that the bench testing that parts stores do are not without fault. If the alternator tests bad, it truly is bad. But if the alternator tests good, it may or may not be good.

I cannot tell you the amount of "escapes" (alternators that test good that are truly bad) that I've seen with alternator testing at parts stores. Many of the testers they use are not comprehensive....

You can however, trust the load testing that they do on your battery.

So let's say they are good. I'm still having same issue. It turns over good,but will only fire up and run if I give it gas and feather/pump gas pedal to keep it running. And it runs good if I keep my foot on gas to keep it idling. It doesn't stumble,misfire or anything. And also,I'm not sure if this is the TCM I'm supposed to be looking for.... it's just to the right of the steering column under dash. Anyone Yay or nay? Sorry these jeeps are all new to me.........
https://cimg0.ibsrv.net/gimg/www.che...a3c6984793.jpg

What are these components attached to throttle body?
 

I know center component/sensor is TPS but other 2? Can't find anything in my Haynes manual.
https://cimg0.ibsrv.net/gimg/www.che...57eb6a01f1.jpg

Bump.......