Have you determined which relay is clicking, do you think it's the E-Fan relay?

And have you positively established it's the IAC pulsing? The IAC motor operation is strictly a function of the PCM. There's no fuses, relays, connectors, or splices between the IAC and the PCM.

Generally speaking, the relays in the PDC and JB have control coils that pull in the power contactor in the relay which powers the device it's connected to. The power to the control coils originates from the igniion switch in the RUN position, except that some require the engine to be started before power is applied to the control coil; the E-Fan relay being one because of it Amp draw. The control over the control coils is from the PCM. The PCM provides a ground to the ground side of the coil when the PCM determines the proper conditions exist to activate the relay.

Most fuses for the relay control coils are in the JB. Corrosion or water intrusion in the JB may short these circuits causing all kinds of odd things to happen.

If you get a chance, pull the cover off the JB and check for white or green residue around the connectors and fuses in te JB. You may want to pull some connectors, relays, and fuses to get a good look.

Here's how you get at the JB:



Here's the JB layout: Fuse 10 is the E-Fan (and Duty Cycle Evap/Purge Solenoid - Clicking?) relay control coil fuse.

 

Will be checking it tom. I can feel ithe iac pulseing so I would say yes def.. The asd relay is clicking also?? jb is another name for Fuse box?? Thanks again Bill

 

With ign., on engine not running I pulled # 10 sure enough the fan shuts off, Still heard clicking Fuse # 11 and the clicking stopped ..From what I can see it looks ok but tom I am going to see if I can get behind it somehow and see if their is corrision behind it?? . I flipped the box on the pass side fender I believe it is called the pdc box and took bottom cover off it is very clean from underneath so maybe something is going on in interior fuse box ?? ,never saw one off a truck looks like a bunch of plugs and two 10 mm nut`s or 7/16 but does not look like an easy job?? But have to look somewhere can not give up now feel like I am close or out of options?? lol Thanks again keep the tip`s coming I do appreciate the help Thanks again, Bill

 

Hi just looked at jb again , it looks like it is pretty clean?? I really do not see any corrision or discolor in or around it .. The fuses all look good but when I first started repairs I did take out every fuse cleaned , inspected it and replaced it.. all looks good even turned key to on position of course relays clicking away and tried moving the wire around.. no change The only thing I did notice was the cable that is under the steering column and I believe goes to the shifter has a roundish looking object about 10 in down from wheel towards pedals seems to be warm to the touch?? I moved it around made sure no wires are leaning agaainst it but no change either.. Should I try to get behind the jb and see if anything is out of the ordinary behind it? I wish I could find a mouse or rat evidence , anything but all looks good ..

 

You should concentrate your search on the AC wiring at the PDC,You said that if you jumped the low pressure switch the fan comes on that is a normally closed switch.That means that is no good.
Check your private messages,A gift for your service and family members.It should help you with this problem and in the future.

 

I'm quite sure that happens by design--the low pressure switch is there to keep the system from turning on when there isn't enough pressure. The reason to jump that switch is to check if your compressor and E-fan works. Should hear a click in the A/C compressor clutch, and the fan should come on.

So, if he were to turn on his A/C, and it were low on pressure enough to trigger the switch, nothing would happen. Not sure there's an issue there besides being low on refrigerant. (but maybe somebody with more knowledge on that switch can chime in)

 

Now with a cold engine I insert key in ign and turn to the run position right before starter engages and you can hear the a/c clutch jumping in and out switch is off and the fan starts to run?
This is from his post,as you can see the system is overcharged and not low,that switch should be closed.And for the fan to come on the high pressure switch has to open the contact for the ac request and close the contact for fan activation,that is why he says the ac clutch is jumping on and off.
Maybe you should do more research,because tou don't know what your talking about.

 

I was going off of threads I've read while trying to figure out why my E-fan wasn't working. I then learned that because my system is low on pressure or refrigerant, the low pressure switch keeps any of it from turning on. I know OP's situation is a little different, but how do you know his system is overcharged?

 

]

prcherokee,

I see you havce a 2000 XJ. The AC system in the 2000 is different than the 1999.

In the '99 system the Low Pressure Cycling Switch (on top of the accumulator) is normally open and when the low pressure side of the system gets to a calibrated value the switch will close. THe High Pressure Cut Out Switch is normally closed and when pressure on the high side side of the system gets higher than the calibrated value the switch opens.

The '99 system is a ground control system. When AC or Defrost is selected on the AC/Heat panel mode selector a ground circuit is passed to the PCM as a "A/C Select Input", and in parallel through the low pressure switch (closed) and the high pressure switch (closed) to the PCM as a "A/C Switch Sense". When the engine is started, the PCM will provide a ground to the AC Clutch relay control coil and the AC Fan relay control coil, which, in turn, will pull in the power contacts of these relays. The clutch will pull in and the fan will run. The relay control coils are powered from the "ST-RUN" bus and the relay power contacts are powered from the "BATT" bus.

From what I can determine, the OP states that the Fan and the Clutch will (uncommanded) run/engage without having the engine running.

He pulled the fan and clutch relay control coil fuse (F10) in the JB and the fan stopped running. Somehow, with the fuse installed, the relay control coils are being activated by the PCM providing a ground to the ground side of the relay control coils (relay pin sockets 85) when it shouldn't.

 

There may be a relationship between the IAC "pulsing" and the AC Fan and Clutch energizing when the key is in the RUN position.

The IAC is powered (from the PCM) when the ignition switch is placed to RUN. When the PCM receives a request for AC from the AC/Heat panel mode selector and the Select/Sense signals through the Low Pressure Switch/High Pressure Swich circuit, the PCM will adjust the IAC motor position. This is done to increase idle speed. If the AC Fan Relay and Clutch Relay are being activated by the PCM for some reason the PCM sees the AC circuit as being complete and will adjust the IAC stepper motor. In this case an intermittant signal through the AC circuit and thus an intermittant circuit to the IAC (Pulsing).

Seven,

If you could detach the connector from the Low Ressure Switch on top of the AC Accumulator then turn the key to RUN and see if the IAC stops pulsing.

~~~~~~~~~

You said that the ASD relay was clicking but stopped when you pulled fuse #11 from the JB. Fuse #11 does provide power to the ASD relay from the ST-RUN bus. The PCM activates the ASD relay through a ground circuit to the ASD relay control coil. This occurs when the PCM is signaled by the crank shaft sensor that the engine is rotating. Somehow power is getting to the ASD relay control coil (pin socket 86) and the PCM is thinking the engine is running and provides a ground to the coil (pin socket 85).

Seven,

With fuse #11 installed in the JB. Detach the crankshaft position sensor at its connector then turn the ignition switch to RUN, then see if the ASD relay still clicks.

 

Now there's some good info! Are 98's and 99's the same, CCKen?

 

Ok tried the low presure switch absolutely no change and tried the crank shaft pos sensosor and also same results no change both relays still clicking.. should I attempt to get behind the jb box?

 

So I decided just for the sake of elimination I removed the jb box from the truck and put it on the bench took out every fuse and relay flipped it over and opened it .. The plastic back and then a metal sheet under that and it absolutely spotless !! no discoloration no burn marks really clean , I was almost hoping their would be a problem or some kind of broken wire or something... lol!! I guess it must be a wire I missed somewhere in the harness ?? If anybody else has to do this it really is not all that difficult a tip you do not have to remove the top mounting nut all the way just back it out and remove the other two mounting nuts (all 10 mm) lift it off gently and it should slide down enough to get the rest of the plugs out.. goes back the same way., I did reinstall hopeing maybe the problem would be gone but no just wish full thinking..

 

The JB sounds like a plan. So far this year I've heard of five cases of bad JB's. Most corroded, but one went swimming.

Make sure the battery is disconnected before removing the connectors from the JB.

Here's what a corroded JB can look like:





Here's an illustration on how to remove the JB:



When you pull the connectors off the JB pay close attention to the connectors for evidence of water intrusion and/or corrosion.

 

I wish mine looked like that? lol dont know how to upload pic`s but mine looks brand new and all the connectors look fresh also?? has to be a break somewhere in the harness?? Bill