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Unread 12-26-2011, 04:05 PM   #1
doggzilla
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99 Jeep Cherokee 4.0 electrical issues on cold start

Before I start, I just want to say thanks to all the guy who have put so much effort into this forum. Sorry for the wall of text.

My 99 Cherokee is having issues starting when around 40 degrees, I have replaced the coolant temp sensor, the battery and cables/terminals, and continue to get cold start issues. It turns over just fine, but wont start. It starts every time if its even slightly warmed up.
The tachometer and speedometer are currently working fine, once in a while it will start without them working and then kick in. That is very rare.
The alternator is putting out 14v according to the gauge, and is charging the battery just fine, but it is an older alternator with a lower amperage. When the original went out, the parts stores had two to choose from, one that was the same amperage and would not fit, and one that was smaller, had a wire harness from the previous model, and so I was forced to splice the wires to get it to work. The live wire to the battery/fuse box appears to be in good condition, but I have not cleaned the wire where it bolts to the alternator. Even with it running 14v, could this be it? Ill try it regardless.
The two smaller wires are spliced, as I stated before, how would dirty connections act? Like I already said, its putting out 14v and charging. Those are only feedback loops, correct? The needle does fluctuate ever so slightly, barely noticeable.
It was throwing a P1694 and P1698, but after a reset it is only showing a P1698 anymore. I replaced fuse #16 and the fuse directly left of it in the PDC next to the battery just before, but neither seemed to be blown. This was to make sure it wasnt the #16 fuse causing the two codes.
A week ago I may have had a short, or it could have just been a really effed up battery, the lights would be on and I would read only 10v, and when I turned the key it would die so completely that the lights could barely be seen. Just instantly suck all the rest of the life out. Happened once more when I was getting a jump.
I am also having an issue with the blinker not working constantly in either direction, and the four way seems to be completely broken. Just saying in case there is some bizarre connection between the two.
I found that the upper O2 sensor wire was pinched between a bolt and the oil pan, but the outer casing seems to be fine. I have read that an O2 sensor problem can kill communication between the ecm and tcm, so just putting it out there.

I have a CPS waiting to be installed, but I could not get the top bolt removed, so I decided to come on here and get some advice after I ran out of time and sunlight. Would a CPS cause a cold start issue?

If it doesnt want to start tommorow morning, Im going to switch the fuel and O2 sensor relays with the AC clutch relay. Can a bad relay stop the 5v line just like a shorted wire would?

Thanks again guys!

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Unread 12-26-2011, 04:16 PM   #2
CJ7-Tim
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The most likely cause is a faulty Crankshaft Position Sensor. Any odd behavior from the instrument panel when this is happening ?

If the O2 sensor or the sensor wires have a short circuit or and open circuit that could possibly trigger a P1694 or P1698.

A faulty turn signal lever/multi function switch or blinker module will cause problems with the turn signals and the emergency flashers, but will not effect starting.

P1694 Fault In Companion Module. No CCD/J1850 bus messages received from the power train control module (TCM) - Aisin transmission.

Possible Causes:
CCD Bus (-) circuit open between PCM and TCM.
CCD Bus (+) circuit open between PCM and TCM.
Transmission CCD bus wiring damaged.
Faulty TCM.


P1698 No CCD Messages Received From PCM. Bus communication failure to PCM. A "Companion DTC" was set in both the ECM and PCM.

Possible Causes:
When the CPS short circuits the engine computer (PCM) shuts down to prevent damage to itself. As a result, there is no communication (P1694).
Disconnect your crankshaft position sensor then put the ignition key in the on position. If the instrument cluster starts to work, once the CPS is disconnected, then you know it is shorted. You can verify this by testing the CPS with an ohmeter.
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Unread 12-26-2011, 04:52 PM   #3
doggzilla
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Thats the thing, the cluster works almost all the time. It is VERY rare for it not to work. I never turns off after I get it running.
One other odd thing, I started throwing a code whenever I ran anything but regular, perhaps the starting issue has nothing to do with the code at all. Perhaps I just have a bad O2 sensor and should treat them as separate issues.

What sucks is that I love this Jeep and I would totally rebuild it to new condition, except that I am living off family while I start a new career in trucking. I dont have the money to do what I want to do. I would just go all out and not even care, whats a grand or two when you love your Jeep?
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Unread 12-27-2011, 10:03 AM   #4
doggzilla
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Ok, so I swapped the relay for the fuel/o2 with the starter relay, and I let the engine prime twice before I started it, and it fired up instantly.
I went to autozone and replaced a bad flasher relay and a new gas cap, and it was only showing a companion code p1694. They cleared the code and it did not return......until I let it idle when I got home. This was after stopping at walmart, so about 15 minutes total. Im positive this has to do with reduced voltage from the alternator, and that the hard starts and code are unrelated. Also, I did not have the lights on when idling at walmart, but did when home, so Im even more sure its a voltage issue.
Tomorrow morning will be cold, so Im going to see if it will start easier between the new cap and letting it prime. Otherwise Im going to clean all the remaining contacts, especially the o2 contact, seeing as the stock fastener places it directly into the firing line of any crap flung up by the wheels and cars ahead of me. You would think they would have tried to protect it somehow.

BTW, dont tape relays, the person before me taped the blinker relay into place, and it melted the tape.
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Unread 12-27-2011, 03:00 PM   #5
doggzilla
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Also, the autozone code reader shows code p1694 as code 16 as well, and P1698 as code 18. What are these codes? Transmission temp sensor, and voltage out of range.

This would explain why it sometimes shifts late, because that sensor can totally screw the shifting pattern.

Thing is, even though I can see that the tranny has the sensor, The auto parts places are saying this part doesnt exist. Argh!
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Unread 12-27-2011, 07:38 PM   #6
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Quote:
Originally Posted by doggzilla View Post
Also, the autozone code reader shows code P1694 ... and P1698 ...... What are these codes?
See post #2 above.

P1694 and P1698 are Jeep troubles codes for OBD-II computers in 1996-2001 Cherokees. Two digit OBD-I trouble codes are non-specific generic codes and can mean different things on different vehicles.

OBD-II is more accurate and more specific as to the malfunction.


P1694 indicates a possible Transmission Control Module fault. Faulty wires, faulty wire connectors, or blown fuses can cause the same code.
P1698 indicates a possible Crankshaft Postion Snesor fault. Faulty wires or faulty wire connectors can cause the same code.
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Unread 12-28-2011, 05:51 AM   #7
doggzilla
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Yes, I saw that post, and all I got was this lousy T-shirt.

I work on Jeep. Jeep start in cold now like new. No $80 part required. Was 32 out, and it fired as instantly as I have ever seen it start.

I work on Jeep, next day Jeep announced most reliable. ^_^

But seriously, I suspect very much that the two coding systems overlap. When you pull the code with the code reader at autozone, it shows that code 16 and 18 are alternates of P1694 and P1698. The first line states what the signal means in old code if there is one, and then after that it shows the new code equivalent.

Seeing as how even a bad bus wire for my A/C clutch will set off this code, Im almost sure that the Jeep itself is meaning this code as low voltage, the two codes just happen to overlap in the two different diagnostic languages. I really do believe this, especially since I cannot find anybody else who has had a hard start cured by replacing the CPS, its always something else. I searched out every post I could possibly find in several forums, and it was almost always some sort of connection or relay issue.
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Unread 12-28-2011, 04:09 PM   #8
oakmckinley
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Well I have had to replace a CPS for hard/no starting.

Aren't you listening to Tim?
If your convinced it's a voltage problem then take care of the problem.
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Unread 12-28-2011, 09:42 PM   #9
CJ7-Tim
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Whatever works for you. I have an inexpensive OBD-II code reader and the two digit codes are nearly worthless for diagnostics and troubleshooting.

I don't go to AutoZone, the counter people are friendly, but know nothing about most vehicles or repairs. The AutoZone database has numerous errors and they will give you the wrong parts.
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Unread 12-28-2011, 09:52 PM   #10
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It's possible that the lower amperage alternator isn't cranking out enough amperage and resulting in fluctuating voltage between different modules and sensors.
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Unread 12-28-2011, 10:33 PM   #11
CJ7-Tim
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Quote:
Originally Posted by jason_guy_yeah View Post
It's possible that the lower amperage alternator isn't cranking out enough amperage and resulting in fluctuating voltage between different modules and sensors.
Amps are the measure of output capacity. If the alternator output is a normal 13.5-14.8 volts (which the battery buffers to 12.5 volts), then it is not the cause of the problem.

Most of the OBD-II sensors are running at 5 volts supplied by the PCM engine computer.
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Between 2009 when Obama took office, and 2013, median annual household incomes have fallen by more than $2,100.

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Unread 08-15-2013, 03:51 PM   #12
doggzilla
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I started another thread I should have continued in here, but oh well.

Im not having engine issues anymore, but the rpm gauge dies and the tranny fails to shift. I replaced the ECM and TCM, but nothing. The RPM gauge starts working again when I unplug the TCM module, but it doesnt shift. I just took it on the road and it will go 45 at very low RPM, so its gone to 3rd gear emergency mode. Takes all your power to get going, but it eventually gets up to speed and drives normal once you get up to speed....

So, either my junkyard tcm is broken as well, or....a shorted wire? What else could it be? A shorted component to the TCM, the temp sensor?
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Unread 08-16-2013, 02:02 AM   #13
doggzilla
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Where did everyone go haha. Sad times...

Anywho, forgot to mention that the A/C is out, and happened to find a diagram that said that two A/C components are on the same fuse, and I had the compressor wire break earlier and I disconnected the pressure switch to make sure that wasnt the short. Im going to hook it back up when the sun comes up and see what happens.

I am certain its not the TPS, and that the other possible fuse or IOD is not blow because it starts and runs like a champ.
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