'98 Jeep not getting right volts to coil

[Datsunchris]

Here is the more detailed thread I posted on wrangler fourms:'98 Jeep not firing, not starting with A/C on. - Jeep Wrangler Forum

Here is a summery;

98 Jeep wrangler, 2.5. Started dieing randomly when hitting bumps, replaced fuel pump, didn't fix it. Replaced old clogged muffler, and it ran great for a month, but now would not fire with A/C or heater on, would have to turn them off, start jeep, then could turn them on. Now the jeep stopped firing all together.

Replaced CPS, no change. Traced the problem to the two coil wires (that give it power).

From what I read, orange wire is positive, green wire is pulsing ground. Tried new ECU, no change. ASD is good, all fuses good. All connectors good. With old ECU, orange wire gets 12v all the time (one lead on the wire, and one one the pos. battery terminal). The green wire only test .080v when starting, and DOES pulse. New ECU, orange wire acts the same, but the green wire is acting JUST like the orange one, with a consistent 12v (again, testing one lead on the wire, and one one the pos. battery terminal). There is a difference between the ECU's, but nether is working. Could it be BOTH are bad? Seems very unlikely... BTW, at no time have there been any codes, other then for the o2 sensor for cat (sensor 2).

please help......

 

[SteelHeadz]

Disconnect the O2 sensor wire then see if that makes a difference. A shorted signal circuit on the O2 sensor can cause a no start.

 

[Datsunchris]

Disconnect the O2 sensor wire then see if that makes a difference. A shorted signal circuit on the O2 sensor can cause a no start.

Tried it, no-go.


I just noticed that I'm testing on the wrong batt. terminal (the pos + side), but I tried testing on the neg = side with no reading from ether wire. I ONLY get a reading with the pos + battery terminal. It's acting like the positive coil wire, is grounded. Where as the pulsating ground, ether isn't pulstaing with one ECU, and doesn't show much of a reading at all with the other ECU.

My last resort before giving up is to pull the dash and look for a short or something (remember, it wasn't starting when the AC or heater was "on"...).

Thanks for the help.