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Unread 04-07-2012, 07:29 PM   #31
CJ7-Tim
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Set the meter to Ohms, the upside down U symbol. Use the 10K or 20K (or even 200K) setting. The meter display will usually display a 1. Touch the red probe end to the black probe end, and the display should change. Mine changes to 0.0, yours should change to some form of 0.

When tested, your CPS should show zero or almost zero.

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Unread 04-08-2012, 11:28 AM   #32
mysnocat
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Thanks for responding. With the meter in the 20K range I am getting a reading of 9.33. I assume this is no bueno as far as the cps is concerned and I should replace it. The strange thing about my particular "won't start" situation is that it will usually fire up if jumped. The battery tested OK at rest and under load although it is getting up there. I bench tested the starter and it is fine. Relay is also fine. Alternator is 14V plus with everything turned on. Ignition switch appears OK.

Am I missing something, because even though my cps looks to be bad, why is my Cherokee starting when jumped if that is the problem? Scratching my head.
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Unread 04-08-2012, 11:38 AM   #33
CJ7-Tim
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Is the no-start caused by the CPS or by the starting/charging system ? The answer to the question, is to test your way to the cause of the no-start.

Every 4.0L XJ Cherokee will need at least one new CPS at some point in its life. Normal CPS service life is approximately 100-150,000 miles
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Unread 04-08-2012, 01:24 PM   #34
mysnocat
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That's what I am confused about. Everything has tested OK excepting the CPS, but what am not understanding is why it would start when jumped, if the CPS is the source of the no-start? I think I will go ahead and change out the CPS as my Cherokee has 150,00O miles on it and I see no evidence of the CPS having been changed in the repair paperwork.

Just don't like changing something unless I am positive it is bad, but the new CPS units on Ebay are as little as $13, so what the hell.
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Unread 04-08-2012, 06:47 PM   #35
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Cheap parts are cheap for a reason. Cheap crappy Jeep sensors are often out of specifications or even failed right out of the box.

Using genuine Jeep or NAPA sensors is highly recommended.
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Unread 06-17-2012, 10:42 AM   #36
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Just wanted to post a big thank you to everyone with Jeep knowledge and the desire to share it.

Last night my '99 XJ wouldn't start, although it would crank all day long. I had the "no bus" error code on the odometer, so I searched this site and found the fix.

I disconnected the CPS wire and the gauges started working again, then I put an ohmmeter on the conductors and found it was defective.

My only problem is the AutoZone Duralast CPS ($71.99 plus tax) pigtail is about 1-2 inches too short to reach the metal mounting flange on the intake manifold. I had to use a zip-tie to hold it in place and prevent it flailing about under the hood. I don't think it would be a problem to leave it loose as the wire is so short that it is basically held taught between the connector and the CPS mount, but it is what it is.

Thanks again!
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Unread 08-03-2012, 08:12 PM   #37
ElColo
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I have a 98 XJ and it has been having issues starting. It has a new battery, new cap, rotor, cables, and plugs. It turns over for a about 8-10 seconds the first time. If I've been driving, it fires right up no problem. If I let it sit for 30 minutes, not so much. It still turns over. Turns over strong and consistent, it just doesn't start.

The only issue I've had with gauges have been the tach and speedo, which I think is an entirely unrelated problem. I saw a technical service bulletin out there somewhere saying the connections in the back of the dashboard are faulty and it specifically mentioned the airbag light, tach and speedo. They died on me going 60 down the highway. Just dropped to zero, but it had no affect on how the car was running and they popped back up.

My Jeep has 113,000 miles on it. Has this issue starting up. Is it worth just replacing the CPS anyway? We have really tough winters here in Idaho, and the last thing you want to do is spend the night on a deserted highway in -20 degree weather...
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Unread 08-04-2012, 02:12 PM   #38
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Quote:
Originally Posted by ElColo View Post
I have a 98 XJ and it has been having issues starting. It has a new battery, new cap, rotor, cables, and plugs. It turns over for a about 8-10 seconds the first time. If I've been driving, it fires right up no problem. If I let it sit for 30 minutes, not so much. It still turns over. Turns over strong and consistent, it just doesn't start....
Sounds like a faulty Check Valve on the fuel pump. You could also have some vapor lock.

Research the failed check valve, heat soak, and vapor lock.

The dashboard issue is separate and if the Jeep runs while it happens, there is no worries. You can try to fix the dead gauges, or you can just live with it.
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Unread 08-04-2012, 08:57 PM   #39
ElColo
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Thanks CJ7-Tim. Yeah, the more I think about it, the more it sounds like an issue with the fuel pump as well. especially with so many talking about the CPS malfunctioning when hot. This might be a stupid question, but would you be able to actually hear the fuel flowing back into the tank or anything when you turn the car off? I swear I can hear a gurgling sound coming from the back every time I park and turn it off. I don't use the A/C so i know it's nothing like that. Just curious. I research it...
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Unread 08-13-2012, 06:56 PM   #40
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Hi All

I found this post and it certainly helped.

One day 2000 XJ would crank all day but no start, fuel pump would not kick in unless I bypassed the relay, still no start, then noticed that gauges would not work, then after a minute "no bus" message. Disconnected CPS and gauges work again, tested CPS and had low resistance. Changed CPS and started right up, found code 1694 after seeing check engine light came on after start up, cleared code and all good so far.

I guess I'll keep a 7/16 swivel head, 20" and 10" extension and 3/8 drive with along w/CPS for long trips now.

Thanks
Joe
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Unread 09-11-2012, 07:35 PM   #41
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Quote:
Originally Posted by CJ7-Tim View Post
Is the no-start caused by the CPS or by the starting/charging system ? The answer to the question, is to test your way to the cause of the no-start.

Every 4.0L XJ Cherokee will need at least one new CPS at some point in its life. Normal CPS service life is approximately 100-150,000 miles
Hi CJ7, I wanted to ask if the CPS can fail even when the Jeep has not shown the "no bus" indication????

My XJ has been stalling when first started, with cold engine like every three to 5 minutes, and when driving in the street, it just stalls at idle.
The IAC valve was recently cleaned, and it have new battery posts. Also, all the connections between the battery, alternator, starter, fuse box, etc, seems to be perfectly tight. The same also applies for the negative side of the battery.
Where should I be looking?

Also, I have noticed that the fuel gauge sporadically, goes all the way to the empty side, when there's plenty of gas in the tank. The reserve light goes on even way before is close to real reserve indication by the needle.



Thanks for the highly appreciated input.-
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Unread 09-11-2012, 07:44 PM   #42
CJ7-Tim
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As in my original posting, the CPS can fail with no symptoms, and may or may not cause No Bus to be displayed or a Check Engine Light.
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Unread 09-13-2012, 06:13 PM   #43
zeuchm
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I thought I had the CPS problem, but now I'm not sure: The symptoms sort-of match--no spark, fuel gauge reads empty--but I can't hear if the fuel pump runs, and when I unplug the sensor the fuel gauge still reads empty (with 1/2 tankful). If anyone had a similar problem and solved it, please let me know.
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Unread 10-22-2012, 07:41 AM   #44
tdstudio
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crank sensor



Thanks so much for the posts on crank sensors.... I put a new fuel pump & distributor cap & rotar..... & finally the crank sensor fixed the stalling of my jeep 1995 cherokee....
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Unread 06-10-2013, 12:16 PM   #45
MDchanic
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Just a quick note -

The sensor plug I found on my 2000 was slightly different than the earlier plugs, and the terminals are numbered by the factory, rather than lettered.

It looks like the scan of the factory manual posted by CJ7-Tim, but that post did not specify how to orient the plug in order to test the right pins.



Here is a shot I took of the 2000 plug, with the terminals labeled.



I got 25Ω between terminals 1 and 2, on my old plug, and ∞Ω on the new plug (which fixed the no-run problem).

Incidentally, once I had hunted down the right combination of extensions and sockets form their hiding places, I had no problem removing and re-installing the sensor single-handedly.
I needed: ratchet, ~18" extension, universal (with a few wraps of electrical tape for some stiffness), ~3" extension (or a deep socket), 11mm socket and a magnetic socket insert to hold the fastener.
Removal was fairly easy, if annoying, and took less than five minutes.
Replacement was more annoying, requiring me to wedge my hand behind the engine from above to place the sensor in position, then carefully place and thread the screws from below, and took about ten minutes.

- Eric
2000-jeep-bad-crank-sensor.jpg  
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