Top 20 1999 Jeep Wrangler - Page 8 Questions & Answers

There is a heater control valve on the heater core hose. This is a common problem on the Jeep Wranglers. The valve is not opening.

This light is problematic as I had to encounter this as well. For what it is worth, the job of removing it to replace a bulb, most likely an LED will not be worth the time. You know you are in 4wd when your steering becomes a bit stiffer and when you make a sharper turn feel your axles kind of bind or get stiff. The steering feels tighter or "heavier" and maybe your power steering labors more in a sharp turn. Once you drive with it on and off and pay attention to these aspects, you will know you are locked in 4wd. You should also feel a slight clunk or release when you are driving and you take it out of 4wd.

check your relays they run on differnt ones for head and parking lights

Check the cap rotor spark plug gap and spark plugs also check the timing get back to me and give me more details sounds smells vibrations

the fuel filter/fuel pressure regulator is mounted on top of the fuel tank between the fuel pump and the fuel supply tube, fuel going out

The temp reading on the dash is a very big clue... Likely the thermostat (at the end of the large top radiator hose inside the metal housing) is stuck open. When that happens, the coolant in the engine never reaches full temp. Not only can that result in a low heat condition but it can also give you poor fuel mileage as the computer always thinks the engine is cold and therefore it adds extra fuel to keep it running.
Replace with a 195 degree(f) thermostat, run the engine (with the heater on full heat) to nearly normal temp, turn it off and wait about three minutes, then re-start and continue filling. Once full, add whatever is necessary to the recovery bottle and close it up and check for leaks.

If the battery just died for no reason, reason being the door was left open too long or a headlight,dashlights were left on or any application on your car was left on then your battery probably just needs to be recharged. If that not the case then it most likey your alternator if that dead then your battery was not being rechared/maintain by the alternator,even if you drove it that drive kill was power your battery had so in that case you will have to replace your alternator

Bad fuel, dirty fuel filter, dirty air filter, dirty injectors. I'm assuming there's no check engine light on. You should get upwards of 20mpg easy. try replacing the airfilter and fuel filter. I would get a K&N airfilter, i've had great luck with them. you should notice amore power and better fuel efficiency. Also, use an injector cleaning additive, like Lucas, and use synthetic engine oil. it cost more, but you'll change it less often and it's worth it. I'm a fan of valvoline. oh, and make sure your tires are inflated properly, that can make a noticeable difference

do you have a digital ododmeter on this model

http://www.jeepforum.com/forum/f11/no-bus-odometer-no-gauges-not-starting-524101/index2.html

Had the same thing with my 2004 Wrangler. The Airbag light stayed on also. Took to dealer - Cost $400 for them to replace the ignition. Fixed every thing.

flush the system

The best fix is to install the two piece OEM manifold from the later model (2000's) wranglers. There are also manifolds with accordian type flex joints for sale on line that will last MUCH longer than the one piece OEM manifolds.

I would check the fuel filter first, because it is easier to check if you do not have a fuel pump pressure gauge, an it is a lot less expensive.. Also check your plugs an make sure they are not fouled out, because if your're having a fuel issue, it will effect the plugs also. By looking at each plug you can determine if you are running rich or lean. Now if your filter is ok, an the pump appears to be working fine, you may want to check your fuel injectors or your fuel pressure regulator.. But a easy way to check your fuel pump without a gauge is to, un hook the fuel line before the fuel filter, get a decent size bottle, an place the line inside of it. Have someone turn the key on.( Do Not ) crank the vehicle up, just turn the key where all the dashboards light come on, an you should get a good stream of fuel coming into the bottle, but if it comes out soft, then yea the fuel pump is weak.. Good Luck.. I hope this info was helpful..

The intake manifold is the common culprit for this. It may look like it is flush to the block, but it isnt and is causing a huge vaccum leak. There are two locating dowel pins that the manifold must be flush on before tightning the bolts. The usual problem is that the manifold is resting on top of these pins instead of flush, causing a gap. You have to unbolt the intake and exhaust manifolds, relocate the intake and replace the bolts.

The tensioner can be replaced as just the pulley, by removing the center bolt on this pulley, to release thee tension loosen center bolt then loosentension bolt on top of the bracket.

If the engine cranks and cranks but never starts ? It's almost always the CPS.



The most likely cause of it cranks and cranks but won't start up is the Crankshaft Position Sensor (CPS) located on the transmission bell housing. Often this part is also referred to as the CranKshaft Position Sensor (CKP) CPS/CKP failure is very common. The CPS/CKP can stop working with no warning or symptoms and the engine will not run or the engine may randomly stall for no apparent reason.

Crank Position Sensors can have intermittent “thermal failure”. This means that the CPS/CKP fails when engine gets hot, but works again (and will test as “good”) when it cools back down.

Begin with basic trouble shooting of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables and replace as needed. Do the same for the grounding wires from the battery and engine to the Cherokee's frame/body. Jeeps do not tolerate low voltage or poor grounds and the ECM/ECU will behave oddly until you remedy this.



Symptoms –
- Starter cranks and cranks but engine won't start up and run.
- Fuel gauge and voltage gauges may not work or display properly.
- You sometimes will have No Bus on the odometer after 30-60 seconds.
- A failed CPS/CKP may or may not throw a CEL trouble code.
- No spark at the spark plugs.
- Fuel pump will run and prime for 3-5 seconds.

If the CPS/CKP is failed sometimes the OBDII code reader cannot make a connection to the computer or cannot read Check Engine Light/MIL codes because the CPS/CKP has failed.


Diagnostic steps to confirm the CPS is the cause of your no-start


You should be able to verify a bad cps, by unplugging it, and turning the ignition key to on. If the voltage gauge and/or the fuel gauge now displays correctly, replace the CPS.

Unplugging and reconnecting the CPS sensor where it connect to the main harness near the back of the intake manifold usually resets the ECU and if the jeep fires right up after doing this you can bet that the CPS is faulty and needs to be replaced.

Exchange the fuel pump relay and the ASD relay with one of the other similar ones in the PDC to eliminate the relays as the cause of the no-start Confirm that the fuel pump to runs for 3-5 seconds when you turn the ignition key to ON.

Eliminate the NSS as a cause of no start. Wiggle the shift lever at the same time you try to start. Put the transmission in Neutral and do the same. Do the reverse lights come on when the shifter is in Reverse?

Inspect the wires and wire connectors at the O2 sensors on the exhausts pipe. A short circuit from melted insulation or from broken O2 sensor wires can blow a fuse and the ECU/ECM will loose communication.


CPS Testing


Crankshaft Position Sensor Connector (CPS/CPK)



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TESTING PROCEDURE 1991 – 2001 4.0L H.O. engines
1. Near the rear of intake manifold, disconnect sensor pigtail harness connector from main wiring harness.
2. Place an ohmmeter across terminals B and C (See Image). Ohmmeter should be set to 1K-to-1OK scale for this test.
3. The meter reading should be open (infinite resistance). Replace sensor if a low resistance is indicated.

TESTING PROCECURE for 1987 – 1990 4.0 L engines

Test # 1 - Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the CPS and measure across the CPS connector's A & B leads. Your meter should show a CPS resistance of between 125 - 275 ohms. If the CPS is out of that range by much, replace it.

Test # 2 - You'll need a helper for this one. Set the volt/ohm meter to read 0 - 5 AC volts or the closest AC Volts scale your meter has to this range. Measure across the CPS leads for voltage generated as your helper cranks the engine. (The engine can't fire up without the CPS connected but watch for moving parts just the same!) The meter should show .5 - .8 VAC when cranking. (That's between 1/2 and 1 volt AC.) If it's below .5vac, replace it.


The 2000 and 2001 will have the CPS in the same location on the bell housing, but the wire connector may be on the passenger side, not as shown in the diagram below. Simply follow the wire from the sensor to the connector.

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There should be a round tag on the drivers side rear of the case. Likely you have some version of an aw4 transmission.

Have you checked your voltage at the switch to see if any is there?

Adjustment is made by loosening the power steering pump. There is a transverse long bolt (jack bolt) right under the pump that is used for adjustment.