Grip

Clock spring.

Pull the horn relay/fuse in the interior fuse box.

Try to start it.

Report back.

DJeXeCute

Could stick a screwdriver in one of the plug boots and hold it up to the block same princible

armymech4

Could be a defective ecu with no bus and no gauges.

CCKen

Check the 5 volt supply voltage to the Crankshaft Position Sensor.

Unplug the CPS connector,

Turn ignition switch to RUN, without cranking the engine,

Using a digital Voltmeter, measure the voltage between the CPS body harness connector pin cavity with the Orange wire to the engine as a ground.

You should see 5 +/- 0.5 volts.

If you see a higher voltage, suspect the clockspring.

If you see a low voltage, suspect the PCM.

If you are getting out of range readings do the same check at the MAP sensor connector and the TPS connector. If all these readings are out of range then it confirms the 5 volt supply voltage is corrupted. If the reading is out of range at the CPS connector only, suspect a bad splice in the wiring harness. All sensor 5 volt supply are carried in an Orange wire, all spiced together, with the origin at the PCM.

If you are using the engine as a ground and get bad readings, switch to the battery negative post as a ground to see if the readings change. If the voltage readings are good now, suspect a bad ground circuit from the battery to the engine and/or to the chassis, in the engine bay. Suspect are the ground point at the ignition coil mount bracket studs (G101) and/or the ground point on the right inner fender (G100).

HudsonN

Tried this. Still no start. My airbag light was on for the past year or so and i just assumed the clockspring was bad but i never did anything about it. Thing started and drove fine without any problems.

Ken, just did what you explained to do and that might reveal my problem.

Disconnected the CPS connector and turned the key to the on position right before the jeep would normally crank.

Put the ground on my voltmeter to the orange lead in the body side CPS harness and the positive lead to the middle connection.

Read -1.093 volts DC. Did the same to the rest of the connections, IAC, TPS, and MAP, and the volts were very similar.

Picture of my battery and a video of me testing the volts. (Going to re-do every single ground on this jeep tonight and see if that helps anything. Figure it can't hurt.)

CCKen

Your video jumped around so much I really could tell what you were doing.

To correct you on your procedure, you should put the Positive meter lead to the Orange wire pin cavity and the Negative meter lead to ground. This would be the 5 volt supply. Your Voltmeter should be set to the 20 VDC scale.

The pin cavity with the Brown/Yellow tracer wire is the Ground (or Return) circuit. With key to ON/RUN you should read around .013-.016 Volts. Disreagard the pin cavity with the Gray/Black tracer wire, this is the CPS Signal circuit wire.

The MAP Sensor and the TPS Ground wires are Brown/Yellow tracer as well, and should read about the same as the CPS ground.

Give it another try.

I did notice that your battery connectors are a bit corroded. After sending this post I will give you a link that shows all the ground points in the engine bay.

CCKen

Go here and review post #49 to see all the ground points in the engine bay.

https://www.cherokeeforum.com/f2/gre...e-6558/index4/

HudsonN

Here are the detailed results from that test. Figured it would be easier if you could just see all of the data.

Pertaining To CPS:

- Positive lead on orange wire negative lead on brown/yellow wire - 1.053V

- Positive lead on orange wire negative lead on;

CCKen

Nicely presented. I like that. Except you look like you are getting mixed up again: "Negative lead on brown/yellow positive lead firewall ground - 0.017V" Why would you do this? The Brown/Yellow wire is Ground. The meter negative lead goes to the ground point (firewall, etc.) and the positive lead goes to the power source (Brown/Yellow wire pin cavity). Try it this way, but may not make any difference.

But what were the results of reading the 5 volt supply voltage from the MAP and TPS.

Avoid using the Brown/Yellow tracer wire as the ground. It' meaningless. Use engine or battery as the meter ground.

If you had the meter set to 20 VDC, the CPS 5 volt supply doesn't look good at 1 + volts. It leads me to think the PCM is bad (seen this before), but I wouldn't jump to conclusions until the results of the TPS and MAP 5 volt supply (Orange wire) readings have been taken. If they are the same, line up a PCM. Make sure the part number on the PCM decal will be the same as the one you're looking at. Don't buy it just yet - not until you've disassembled and scubbed clean all ground points in the engine bay. And take all meter readings again. No need to spend money unless you have to.

Note on the grounds: DO NOT USE DIELECTRIC GREASE on the ground ring terminals.

HudsonN

Let me explain my confusion to you.

If the brown/yellow wire is the ground how can it also be the power source? If i put my meters negative (ground) lead on a grounding point (firewall, battery negative, etc) why would i put the postive lead on the brown/yellow wire? I thought you just said that was a ground? Am i confused or are you confused here? Haha.

Actually, i didn't read those for their 5 volts. Let me go check that for you. And just to clear things up to do this i am going to put the negative lead on my meter to the firewall ground and the postive lead to the orange wire on the MAP and TPS. Corrcet?

Sorry for asking you the same thing over and over again. My minds just not wrapped around it yet. Haha.

CCKen

Hang in there bud.

HudsonN

Alright got it now ... I think.

Other Notes;

- No Spark. (Confirmed with one of those spark tester doohickeys.) Hooked it between the coil and the distributor.

- Still don't hear the fuel pump.

Negative Lead On Battery; Postive Lead On Brown/Yellow Wire:

CPS; -0.009V

TPS; -0.009V

MAP; - 0.009V

Negative Lead On Battery Post (-); Positive Lead on Orange Wire:

CPS; 1.693V

TPS; 1.684V

MAP; 1.685V

HudsonN

Double Post.

CCKen

Those Browwn/Yellow wire reading are understandably low because the 5 volt supply voltage is too low. 1.6xx volts in the 5 volt supply circuit is way to low. Generally it's the PCM at fault causing this.

CCKen

Bedfore condemning the PCM, you should diassemble and clean the battery post connectors and ground G101 (ref pic in link in post #22). G101 is the ground for the PCM.

Also, remove the Black connector (C1) from the PCM and see if the pins or pin cavities are corroded.