QuestionQUESTION: Sorry Roland, I did not see a link for a follow up question. You asked if I noticed my fan not coming on as the temp gauge moved toward H. I have actually noticed the opposite. My fan seems to cycle on and off with very little rest time between cycles. I have no over heating issues. I did mention the fan cycle to someone recently as they were checking the refrigerate(sp)and was told the refrigerate was good and the cycle was "normal". Since I see the fan cycling on and off, can I assume my cooling fan relay is good? I also checked the 40amp fuse in the PDB and the 15amp fuse in the panel box, both good. I can see my A/C clutch cycle on and off and I can see the A/C fuse is good. But, something strange happened! As I was replacing the cooling fan (15amp)fuse in the panel box, I accidently placed it in a slot deemed "open" and my A/C began to work. I removed it and it cycled off. I now have a fuse in both slots and it is still working!? I have had it scanned again today at two autoshops and a garage and all still show 0705/1491 but all agree the cooling fan is working.
ANSWER: Hi Theresa,
If you find that the relay is mounted on one of the frame metal structures, as opposed to being in the fuse box, then it is likely a solid-state type of relay which has a higher likelihood of loosing its 'control' properties and turning itself 'on' when not asked to do so (Chrysler had a recall on such a relay in their minivans in the latter 90's so see if that might not also be the case for the Jeep that you have). If you have noticed that the fan comes on before the temp gauge gets to 1/2 scale that would be suspicious of that sort of a problem. I can see whereby if the fan comes on too soon it will reduce the operating temp of the engine which would increase pollution and thus be the rationale for a 'check engine' light coming on. So rather than not working at all, it may well be working too well. If the control circuit turns itself on that would be thus the basis for code.
So check out the specifics of the relay location and then try shaking the wires while the engine is running to see if you can cause it to start up and shut off at random related to the shaking. If that were the case then the wires need to be checked for a bare spot which is touching to metal. If on the other hand it comes on early and cycles on and off frequently then that too may be an internal shorting of the relay which then would suggest replacing the relay. If it is mounted to the frame rail you may have to take a drill or pry tool to open up the rivet that secures it in place. That attachment is important because it allow heat generated by the relay to be dissipated safely to protect the relay function. So the new relay should be firmly re-attached to the frame.
That is how I would recommend that you proceed.
Roland
---------- FOLLOW-UP ----------
QUESTION: The fan relay is in the PDB. I was told about a recall when I first started with this MESS and took it to the dealership, but was told the jeep was not included.I have replaced the fan relay and still receive the same codes. I disconnected the battery for a minute, pumped the brakes ten times, replaced the battery cables and the light came back on within minutes. The auto shop where I bought the relay said the code would have to be cleared by a mechanic after providing proof I had indeed "fixed" the problem. He also said the 0705 code would trigger the check engine light if it were out of "range". But, he is not a Chrysler mechanic. What now?
AnswerHi Theresa,
As I said at the beginning of this discussion I don't have the '99 Jeep manual. Now that I look over the other Chrysler vehicles in this time frame the 1491 sometimes does cause the light and somtimes it doesn't, depending upon which vehicle is in question. The one manual I have about the 0705 says it doesn't but that may not apply to your Jeep. So I really don't know what to make of the situation. Even the code erase issue is not clear, and in any case I don't have the Jeep manual. It may well be that disconnecting the battery won't erase the codes in your vehicle. I guess I have to say that I have run out of advice. Please let me know how you work it out.
The other confusion is that the pcm was changed so there is also the question why the 0443 is no longer present, and that the 1491 appeared with no definite indication that the fan circuit is not responding properly (but we can't be certain in what way it is not responding properly). I don't think this is anything expensive to fix but it probably needs a sharp mechanic. Ideally the person who did the pcm replacement would be competent to sort this out.
Roland
PS: I also would suggest that the mechanic who removed the old PCM put it back in place and erase its codes. It should still work and not need to be modified, and then see after driving the vehicle what codes does it show. If it still shows the 0443 code and not the 1491 and not the 0715 then I would address the 0443 code (which is probably a matter of checking the hoses and clamps of the vapor recovery system for a loose fitting) and that would quickly get you in position to have the smog test. It is strange that the 0443 problem wasn't seen by the repleacement pcm and also that the codes it is saying are now present don't seem to be manifested by the behavior of the vehicle. I see no basis in fact for replacing the pcm in the first place.
