CCKen

Here's an image of the FP connector pinout. It's the harness connector view, not the FP pigtail view.

Also, I've posted a modified diagram of the FP circuit that shows the relay socket wiring.

The FP power and quantity wiring goes through the firewall then through the inside of the Jeep, imerging out under the chasiss near the FP. The FP module ground is behind the spare tire mount in the cargo bay. None of the FP wiring will be in the loom for the O2S and TC switch wiring.

View this Connector Pinout. Is there a possibilty when you read 1.25 volts at the connector you were reading the fuel level sensor wiring?



Here's the FP circuit. You can check the FP relay control coil circuit using a voltmeter in the following manner: Remove the FP relay, Igintion switch OFF, Meter (+) probe to pin socket 86, (-) probe to ground. You should read .00 volts; (+) probe to pin socket 85, you should read .02-.03 volts.

Ignition switch to RUN, (+) probe to pin socket 86, you should read battery voltage (12V); (+) probe to pin socket 85, you should read .02-.03 volts.

The .02-.03 volts on pin socket 85 may be as high as 1.21 volts. This voltage shows the wiring to the PCM that provides a ground to the control coil is intact. This voltage is the PCM idle voltage. The PCM is waiting to be awakened by the start-run CPS activity.

The ASD relay circuit can be checked inthe same manner.

If there is no .02-.03 volts at pin socket 85 either for the ASD or the FP the PCM is dead (no power to it) or the wiring is open. Power to the PCM for this is from fuse 11 in the JB (start-run) for both the ASD and the FP.

gottarollwithit

Most interesting!

So...Test results are as follow:
Ignition off - socket 86 is 0v, 85 is 0v.
Ignition on - socket 86 is 12v, 85 is 0v.

Test results are the same when testing FP and ASD relays.

So... Either my PCM is dead or isn't being woken up? I'm not really sure what to think...

And... the 1.25v at the FP connector could very well have been for the sending unit. Is it really only supposed to draw 1.25v?

CCKen

No sense guessing about the 1.25V at the FP connector at this point.

What voltage range did you have you voltmeter set at when you measured pin sockets 85?

See if you can perform the tests of the CCD Data Bus, as listed in post #6 in this thread, then get back. Maybe this will tell us why you have zero volts at pin socket 85.

http://www.jeepforum.com/forum/f11/dead-gauges-1437129/

Edit: Not mentioned in the tests in post #6 is checking for .02-.03 volts.

Set voltmeter to 20 VDC,

With the ignition switch off/lock and key out,

Touch DLC pin socket 3 with meter + probe and - probe to pin socket 4 and then 5, you should see .02-.03 volts.

Same test of pin socket 11, again you should see .02-.03 volts.

Edit Again: LOL

With zero volts at pin sockets 85, and at the DLC, it may mean the PCM is sleeping (I hope that's all). Try cycling the ignition key to RUN then back to OFF/LOCK, key out, and try reading for .02 volts again.

CCKen

When checking your wiring harnesses for damage, check these ground points on your engine. G101 is the main ground point for the PCM and G102 is the ground point for the DLC. Check for loose connections and corrosion under the terminal ends. G101 is at the ignition coil mount and G102 is at the engine oil dipstick tube mount bracket.

madmax4100

im having the same problem with my jeep exept that my fuel pump is running non stop not sure if i have fuel pressur at the rail but i do know i do not have spark and none of my gages are working when i turn the switch on

gottarollwithit

Grounds seemed tight and not the problem. Twas one of the first things i looked at.

If those are grounds in the picture you posted, where do i test power to the coil at??

When testing for the .02v at 85 in the relay from the post before last, i'm pretty sure we indeed did have 0v. The meter was set at 20v, which granted isn't ideal, especially b/c i have a not so great Harbor Fright multimeter, but i'm pretty sure it's actually 0v.

DLC Tests:

Ignition off/key out:
Socket 3 to 4 and 5 – both 0.015v (measured with meter settings at 20v, then at 2v, then at 0.2v)
Socket 11 to 4 and 5 – both 0.015v
Ignition set to on (position 2):
Socket 3 to 4 and 5 – both 2.5v
Socket 11 to 4 and 5 – both 2.5v

Did not do the resistance test between socket 3 and 11 since this requires removing the negative terminal from the battery. The guy before me rounded over the nut for the cable - i think i'll vice grip it off soon.

Any new thoughts??

CCKen

Please start a new thread on this. Thanks.

CCKen

Here's the ignition coilconnector pin out.

Pin 1 comes from the ASD relay when the relay power contacts are made. When battery voltage leaves pin 87 of the relay it goes through fuse F21 (20A) in the PDC, then to the ignition coil connector. You would want to jumper pin sockets 30 and 87 of the ASD relay base then check for battery voltage at pin socket 1 of the ignition coil connector to ground. The key doesn't need to be in RUN for this. Pin socket 2 of the connector is the driver from the PCM. The PCM turns a ground on and off in the coil primary winding to excite the secondary winding of the ignition coil....fires the plugs.

Connector:

CCKen

Like has been said in an earlier post, repair the wiring at the downstream O2S and the TC Mode Switch before proceeding. If neccessary, get new harness sections with connectors from the bone yard and splice them in. It may also take new sensors.

A word about jumpers in the relay sockets - You should avoid shoving paper clips in the relay base pin sockets. It may enlarge the pin socket to the point where there is no contact between the relay blades (pins) and the pin sockets. I use the male end of electrical quick disconnects. Use 12 Ga. wire and quick disconnects with .250 wide blades. The ones with yellow insulators are for 12 Ga. wire. You can get them at O'reilly or other auto parts stores and at Home Depot or Lowes. You can also get 1 foot sections household 12 Ga. stranded wired at Lowes or Home Depot.

I made a switch jumper for testing my FP circuit (87-30). The set up in the pic uses a 15 amp switch and 18 Ga. wires and quick disconnect blades. This set up is not good for ASD or cooling fan power.

gottarollwithit

So, how do i test my transmission speed sensors for function? Supposedly there is an ohm test?

Anybody know exactly what the rubber mushroom shaped thing is that has a wire protruding from the top of it, that is a couple inches away from the rear trans speed sensor?

Might not be the most sophisticated of thoughts, but my idea is to just remove the entire rear harness and get a new one. That way i eliminate wiring from my list of possible problems... Thoughts?

CCKen

Here's a pic of the left side of an AW4 that shows components. Hope it helps.

gottarollwithit

Time for an update.

I replaced the rear wiring harness. The downstream 02 sensor, transfer case light (4wd) switch, and thingy on the back of the transfer case all are on one harness. This same harness leads up to the engine bay, where it links up with the main harness, coil, cam sensor, and engine grounds. It also snakes towards the PCM, where it feeds into the fuel injectors, crank sensor, MAP sensor, PCM, and other stuff on he intake and throttle body.

The good news is that if i jump the contacts at the fuel pump relay, i now develop fuel pressure. Yay! Bad news is that if i turn the key to Pos 2, it doesn't kick the fuel pump on. I suspect a bad PCM.

I still have dead fuel and voltage gauges. I tried unplugging the CPS again and the gauges remained dead. And... now the airbag light comes on. Does this mean anything?

Outside of a dead PCM or CPS, anything else this could be??

CCKen

gottarollwithit, how are you making out with your project?

Are you waiting for Santa to bring you a PCM?

Here's some reading about replacement PCM's. It's a long read but it's educational.

http://forums.cnet.com/7723-7811_102...esson-learned/

Divine Impressions

Ok Everyone who posted and helped me with my engine swap issues...I have finally gotten My Jeep back on the road.*After months of headaches and trying just about Anything, I had to take the jeep to the dealership; and for the"small fee" of $395 I got a new key w the chip in it and my PCM to communicate w engine... However that still did not fix jeep; the problem was with the ASD relay from the PDC; A wire was broke and had to be replaced! The ASD (Automatic Shutdown) was not communicating w the PCM and after replacing wire THE JEEP RUNS BEAUTIFULLY! No more SKIM issue and/or PCM Issue. I no longer have the key void on dash and jeep runs perfectly! The ASD was not allowing the fuel pump or the coil rail to spark; thereby giving me months of Pain in the Asssets; However I have a new key and jeep is fixed!*THANK YOU TO EVERYONE WHO POSTED & HELPED ME ALONG THE WAY!

Go back and read all my posts and you'll see I had ALL of same issues but the ASD relay was the problem! Make sure it is communicating w PCM and allowing for spark and fuel!

CCKen

Thanks for the follow up, and good work getting it fixed.