Hi there

Thanks everyone for this great forum, it has helped me a lot since I have become a Jeep Cherokee owner.

I have a problem which has been questioned before, but I just can't figure it out and I haven't found the answer reading the other threads about my problem ( P1698 ) - so now I'm making my own.

I have a Jeep Cherokee 1998 Sport 4.0.

Sorry for the long story :-)

A few month ago ( approx 3 ) my check engine light came on and I got P1698 for the Transmission Control Module. I felt a small RPM jump/rough idle feeling and the light came on shortly after - everything still felt fine and drove fine and transmission shifting smooth. Drove 10 miles home and a couple of errands and the engine light went off.
The next morning still no engine light, but came on again after a small trip.
The RPM's started jumping a bit more and more often and the needle would jump too. When accelerating it would continue the rpm jumps and the car bouncing too until reaching 15-20 mph and it would then run fine and shifts fine. It could then drive fine for a while, but then happen again.
Took it to my mechanic and the battery was reading bad, the recharged it and the problem and P1698 went away. Drove it for a month, 5 days a week and no problems. Then the same thing happened again and the engine light came on.
In the exact same way where you almost dont notice anything in the beginning and then the jumps get worse. Took it to the mechanic again and he was sure it was the battery, found out the battery was too small and got installed a 660CCA battery. Problem solved, no check engine light came back on and drove fine. Now another month after battery change, less driving - approx 400miles this time - the same thing happens AGAIN!

So I'm wondering how the problem can disappear and then come back again?

My next steps are to follow the instructions in the other threads and clean my grounds ( as they are dirty and needs cleaning ), also cleaning throttle body and idle air control valve.
I know my distributor cap, rotor, ignition wires and spark plugs are old and needs to be replace, but haven't gotten any misfire trouble codes.

A couple of things to mention, don't know if it can relate to the problem.
It already has a rough idle ( needle would move a little, but no RPM jumps )
Rattle from or around catalytic converter, my old mechanic didn't diagnose it as broken and it did pass smog with the rattle - but did not fix it. Doesn't seem to be the heat shield.
Now and then I get a squeal when I start the car cold ( not cold outside - I'm in Los Angeles ). Squeal disappears right away and mostly seem to happen it has been parked in the sun and the belt might be a little damped. The belt is brand new.

Sorry for all the writing, but thought all the details would matter!

Thanks again for your help!

 

https://vimeo.com/180044474

Here is a video showing a bit of what its doing, it would jump more than this. Sometimes the needle would go above 2k, but the RPMs would stay around the 700. Sometimes the RPMs would go to 500 and feel like its about to die.
At point it sounded like it would let more fuel in, like I was pushing the gas pedal.

I hope anyone can help!

Thank you very much

 

UPDATE:
So today something new happened.
I start the car and notice the voltage is too low, only around the 12v mark on the gauge.
I plugged my battery tester to the battery and it was showing that the alternator was not charging. I keep the car running for a bit and suddenly the alternator starts charging, but then stops again a minute later. It's would continue to do so.
Hopefully someone will reply soon!

Thank you very much

 

Suggest that you address the ground points (G101 and G103) at your coil mount studs (see pic).


Remove the wire ring terminals from the studs and polish them using a Scotch-Brite pad or 400 grit sandpaper then reattach them securely.


Note that the Alternator ground (G103) is there as well as the grounds for the TCM and PCM (G101).



.

 

Hi Ken

This is great, thank you very much for your reply.
I have tried locating these before - is it correct these are the two I see on the engine block near the alternator?

Unfortunately I had to go away for the weekend, but will take a look at this on Monday.

Thanks again for your reply, really appreciate it!

 

Yes. The coil will be mounted to the two studs.


Be careful removing the nuts, those teeth on the Keps nuts dig into the ring terminals and freeze in place. Use penetrating oil on them the day before you plan on taking them off.

 

Hi Ken

Thanks again for your help.
I thought I would give you an update.
I managed to get time to clean the grounds today and cleaned all of the grounds I could find under the hood.
It was definitely needed, especially the ones you pointed out.
I took my time and everything got very clean.
Since I had disconnected the battery to do this, the check engine was gone when I connected everything again and everything seemed fine on my 20mile test drive and the alternator didn't cut off.
Hopefully this have solved the problem :-)
I will give it some time to see if it comes back again.

 

Thanks for the follow up. Hope it works okay from now on.


Those (unfixed) connections sure look nasty.

 

Yeah they were pretty nasty.

It's still well after 50miles now although I'm still getting my slow start, which feels like weak battery. This morning the battery was at 12v and moving a little up and down. Alternator keeps it just below 14 after it started. After my trip battery seems to be reading 12.6.
Need to get a voltmeter to get correct reading.
The starter was replaced in March and battery is only 1 months old and is an 660CCA.
Battery connection are clean and the terminals are newer too - but wondering if the cable is weak / old.
Ken do you know where the ground for the starter is, is that by the coil that I have already cleaned?
When car is cold ( warm weather ), it's a little slow start ( weak crank ) - not much to worry about, but think it's somehow related to my problem.

 

The starter bolts serve as ground, by way of the transmission. It is an indirect path to the battery. Taking care of the main grounds as you have done should take care of the starter ground. They are good and shiny, yes? Any bolts or studs must be good and clean as well.


Check for voltage drop.

Pulled this from JeepForum, posted by CJ7-Tim. Old post from 2013. The OP had been experiencing a slow crank.

Place your DVOM (Digital Volt Ohm Multi-Meter) on the 20 volt scale. First check battery voltage by placing your multi-meter's positive lead on the battery's positive post ( the actual post, not the clamp ) and the negative lead on the negative post. You need a minimum of 12 volts to continue testing. Next, leave your meter connected and take a reading while the engine is cranking. Record this voltage reading. Now connect your positive lead to the battery terminal stud on the starter and the negative lead to the starter housing. Again, crank the engine and record the voltage reading. If the voltage reading at the starter is not within 1 volt of battery voltage then you have excessive voltage drop in the starter circuit.

Typical voltage drop maximums:

• starter circuit (including starter solenoid) = 0.60 volt
• battery post to battery terminal end = zero volts
• battery main cable (measured end to end) 0.20 volt
• starter solenoid = 0.20 volt
• battery negative post to alternator metal frame = 0.20 volt
• negative main cable to engine block = 0.20 volt
• negative battery post to starter metal frame = 0.30
• battery positive post to alternator b+stud = 0.5 volt with maximum charging load applied (all accessories turned on)

 

Hi fb97xj1

Thanks for your reply, I appreciate it.
I did not get to clean to starter bolts as I didn't know they were its ground connection - I will get to that.
So far, still no engine light is back on for P1698.

Still getting my slow starts, even today with battery reading 12.6v.
I'm sure something is draining my battery though - not sure if this can eventually cause my check engine light and P1698 again.

Yesterday evening battery was reading 12.6, car was off for a couple of hours so it will still close to 100f degrees. Easy start!
Should the start be different from when half warmed up and cold?

I followed another thread on the forum and went through my fuses.

I disconnected the negative cable and when reading on the negative post on battery and negative cable it would get up to 0.77 amp - but then drop again to zero. It would almost hit 0.77, but sometimes go up to 0.9. It would stay for a couple of seconds and then to 0.

Of course the last fuse I checked was the IOD, with that removed I would be at 0.

I do have keyless entry and my window master switch is faulty ( window lock button ).
I have taken out my under hood work light as it was not working and I have taken out the bulb by the passenger leg room as it was broken.
And my front speakers are not working.

Just received my new window master switch today which will be installed tomorrow.

Can these things be the cause of my draw?