Cherojakee

97grand4.0

As far as testing the relay socket, pin 30 should be hot at all times per the Factory Serviced Manual. Cranking the ignition switch energizes the relay coil pin 86 which is an electromagnet. You see -12V because you have the meter hooked up backwards. The magnet then pulls in the relay plate which connects pin 30 to pin 87, pin 87 is wired directly to the starter solenoid. Per the FSM you should check continuity between pin 87 and the starter solenoid. The solenoid itself is a relay on the starter, once you energize the coil in that relay, that magnet pulls in the contacts that connect the battery right to the starter motor and will flow up to around 160 amps.
By the way...reading the relay test here....Have you tried starting this in Neutral just for kicks? Because the coil for the relay grounds through the NSS.

jordan96xj

Some of the symptoms we covered before seemed suspiciously ignition-switch related (for example, problems with the radio will never be PCM related), but where the ignition switch appears to be in proper working order (provided the connector has been tested with a multimeter) can implicate the connector that sits right behind the internal junction block (C201 connector? can't remember). The back of the junction block enters the engine compartment though a large connector that is tucked right down in the back corner of the engine compartment on the drivers side. Just below and to the side of the brake booster. This connector can get moisture intrusion over time, and also was greased internally from the factory, and the grease tends to dry and get carbonized over time. If it is starting to cause problems you can get all sorts of ignition and internal cabin (radio, cigarette lighter, etc) type problems because most of the internal power comes through there.

This connector is a little strange in how it comes off/on, it uses a fastener that acts a little like a set screw that helps to pull the connector apart, and draw the connector closed when putting the connector back together. So it can not be simply pulled off by hand and checked. It is well worth your time to open the connector and clean it up, then re-regrease the pins with clean dielectric grease. Its good preventative maintenance in any case, and my very well be involved with the symptoms so far.

I think the OP mentioned radio power weirdness (am I right?) if that symptom came about at the same time the starting problems did...that definitely implies that the PCM may not be the culprit.

Cherojakee

jordan96xj

I better go back and review. This is a long thread, perhaps he did not mention a radio related symptom.

He mentioned this:
So, when I walked away from it last night my gauges worked and I could hear the fuel pump running for a second or two when i turned the key. Still no start but at least consistent. Went out this morning to work on it....no gauges, no fuel pump, and now the radio stays on all the time even without the key in it.....I don’t generally believe in the paranormal but I’m thinking either gremlins or something of that ilk.....

Yes, in summary it is a crank-no-start.

djgrayxj

Note from DJ
I ‘Will save you the time of looking jordan
See post 35 by OP on 7-14-18
Quote:
“So, when I walked away from it last night my gauges worked and I could hear the fuel pump running for a second or two when I turned the key. Still no start but at least consistent. Went out this morning to work on it....no gauges, no fuel pump, and now the radio stays on all the time even without the key in it”.

jordan96xj

No gauges, no fuel pump, and a radio that stays on has the hallmarks of an ignition switch problem where the internal contact rings have come out of their normal position. Such that the ignition switch is basically in the "accessory" position even when other positions (e.g. start/run) are selected. At this point, I would want to fully test the ignition switch (disconnected) and ensure that every pin on the connector is doing what it should be in every position of the ignition switch.

The OP appears to be away from the thread for a bit. He's probably going to be overwhelmed if/when he returns.

SV Forty Two

Still no change, I am at the point where I have two options, try and find an inexpensive pcm that I can try or have it towed to a garage and have them deal with it. I think if I can find a relatively cheap pcm 40-50$ or so I will go that route. I will of course update when/if I ever get this figured out! All of the replies and suggestions have been wonderful and tremendously appreciated.

PatHenry

Did you fully test the ignition switch as Jordan suggested? Jordan is extremely knowledgeable, especially re: electrical and testing related things, you would do well to follow his advice.
I went through 2 ignition switches on my 00 TJ (it uses the same part as the 97+ XJ), and it's very easy to remove/replace and isn't overly expensive.

I would test the ignition switch and be fully sure that it's working correctly before worrying about a PCM. Remember the PCM must be the exact same part number on the replacement. If you are limited to $50 cost, you pretty much have to find one at a junkyard or via somebody parting out a Jeep (remember, part number match, so it's possible the TJ used the same part number). Most aftermarket rebuilt PCM's are at least $150 and usually run in the $200 range.

djgrayxj

Note from DJ

OP it’s your Jeep so the decision is up to you as to how you proceed with its repair.

If it were my Jeep I would start by trying out some of the things that have already suggested.
1. You were asked to unplug the three connectors that plug into the PCP; no reply regarding this suggestion. If this was never tried I would start by trying this first. Remove the negative battery cable and remove each of the three connectors on at a time; give them a good look over for any signs of corrosion, if no corrosion is present then I would plug and unplug each connectors at least four times. This will help clean the pins of the connectors. Reconnect the negative batter cable and try a startup attempt.

Post back the results.

Now I have a question for you do you have a computer or just a smart phone. The reason I’m asking I have some information regarding the ignition switch which is kind of wordy and involves the posting of some photos. If you only have a smart phone you don’t have a very large viewing area is all.

I will wait to post the ignition switch information till you post back.

SV Forty Two

I did unplug the three connections going into the pcm and they looked fine to me. Sorry for not adding that info in, Have been trying to update with what I had done, but omitted that piece! I will try to disconnect a few times to see if that cleans anything up, I didn't notice anything, but I am sure it can't hurt. I do have access to a computer, so any info you might have re ignition switch would be wonderful. Thank you.

SV Forty Two

jordan96xj

It makes me glad to see this resolved. It also goes to show that while the PCM is not typically the failure, that it certainly can be. Certain vehicles have a reputation for chewing through PCMs (mostly due to poor heat management and water intrusion due to poor location). Thanks for the follow up!

By the way, a bad PCM never caused a radio to stay on in the XJ. So how is that symptom going?

Cherojakee

SV Forty Two