TN-XJ said:
ok, a quick update
I replaced the CPS and still no go,
I think I might have a bad coil even though it tested good,
I checked the power to the control module and this is what I got, both while cranking and with the switch in the run position
plug 1, with one yellow wire ~4.6 to 5 volts
plug 2 yellow wire ~11.0
black wire nothin'
green/white wire nothin'
it seems right to me which means the coil is dead, any thoughts?
The small yellow wire is the pulse wire that comes from the ECU (computer), your tester seems better thn most, you got a reading (this takes a special tester to affectively test). The large yellow wire is power, when the key is turned on. Black is ground. Green is the tachometer wire. Might want to check the ground, just to eliminate that.
Crank position sensor, sometimes called the engine speed sensor among other things. Jeep has a habit of changing the name when they change the model run. I once ran my Renix for weeks with the cam position sensor disconnected, so I doubt it is essential. Though if it was shorted it may cause problems with the low voltage supply circuit from the ECU, which could affect the CPS (and other sensors).
A quick coil test, ohm between the plus and minus about 1 ohm, between the plus and the high voltage about 8-9 kilo ohms ( or 7-11 kilo ohms it's not exactly a percision item).
Coils don't often go bad. The ignition modules don't often go bad. the contacts between the igintion coil and the igniton module get kind of green, white and corroded on occasion and the high voltage wire from the coil to the distributor cap goes bad and shorts. Water gets into the distributor, high voltage wires, boots and causes ground paths.
The wires to the CPS often cook on the exhaust manifold and can short. Which rarley causes any lasting damage. The connectors between the CPS and the ECU (3 or 4 depending onthe year) get corroded. The CPS is a fairly low output component, it doesn't take much resisitance to cause a signal too weak to do any good.
Check the wires to the CPS (closely) and clean the connector, and then clean the next connector.
Make sure you tightened the CPS down completely and it is sitting in position correctly. The bolt heads are flush and you used the original bolts.
Possible a CPS wire *after* the first connector, right where it goes into the injector harness has been shaking up and down for years and finally fatigued all the way through the copper under the insulation. Squeeze the wire gently between your finger and thumb nail on the insulation and feel if you find a soft spot.