Check the coil for voltage in?

 

Check the CPS like this:

Renix CPS Testing and Adjusting



Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.

Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.

The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.

Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.

You should get a reading of .5 AC volts.

If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.

Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.

A little trick for increasing the output of your CPS is to drill out the upper mounting hole, or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.




Revised 07-30-2012

 

This is NEVER a bad idea:

Renix Jeep ICU/Coil contact refreshing



The contacts between the coil and the ICU on your Renix Jeep can become corroded and loose causing a complete or intermittent no-start condition. I recommend the following procedure as a maintenance precaution to insure this is eliminated as a possible cause now and in the future.

The coil is attached to the ICU by two T20 Torx bolts. Remove these two bolts and lift the coil up off the ICU. You will see 2 pins and 2 sets of contacts. Clean both the pins and springy contact pieces with a good electronics cleaner.
Squeeze the springy contacts closer together with some needlenose pliers. Apply some dielectric grease to the contacts and bolt the coil back on to the ICU.
While you’re right there unplug the connectors from the ICU and inspect the pins in the harness connector. Make sure the pins are not retracted into the connector. Spray out the connector and the receptacle of the ICU with the same good electronics cleaner you used earlier. Apply dielectric grease to the connectors and plug them back in.

I feel this procedure should be performed at least once in the lifetime of a Renix Jeep.


Revised 11-29-2011

 

Nor is this:

Renix Ground Refreshing

The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.

The components grounding at the dipstick tube stud are:

Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.

The factory was aware of the issues with this ground point and addressed it by suggesting the following:

Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud's mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.

Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn't hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.

While you're in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.

Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver's side of the firewall. This cable is undersized for it's intended use and subject to corrosion and poor connections at each end.

First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3'4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.

A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.

A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.

If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.

Revised 11-28-2011

 

I went and checked to see if i was getting voltage to the cps and im not. Im not getting anything to the cps. Would i need to look into a new ecu for this then since im not getting voltage to the cps? I have no problems with getting the motor to turn over but just not getting any spark to make it run.

 

CPS makes it's own voltage. You check it like this:

Renix CPS Testing and Adjusting

Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.

Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.

The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn't generating enough voltage to trigger the ECU to provide spark.

Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won't start with the CPS disconnected.

You should get a reading of .5 AC volts.

If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That's a definite no-start condition. Best to buy your CPS from Napa or the dealer.

Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It's worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.

A little trick for increasing the output of your CPS is to drill out the upper mounting hole, or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.

Revised 07-30-2012

The 3 wire connector goes to the front of the ICU.

 

Also went and cleaned the pins on the coil where it goes into the ICU. I know that the 1 wire 2 prong plug goes in the middle. Where does the other plug go to? Is it in the spot towards the front of the jeep or the rear of the jeep? Don't know if this would make a difference or not.

 

Yes that is the way that i checked for the voltage at the plug for the cps. From looking around it looks like it is not getting a signal from the ecu. The old cps had the wires get burnt on it and they had touched together and i think that is what caused everything to short out. Wondering if this didn't take the computer out as well. Any thoughts?

 

The CPS DOES NOT get a signal from the ECU. It generates it's own.

 

I will check it again tomarrow. Does it matter which lead from the meter goes into which part of the connector? It is a new cps I got from Napa. Where should I go from here.

 

Doesn't matter which lead goes where. Set you meter to AC volts.

 

Had my dad come over and help me test the cps and i am getting around .6 volts coming from the it. I think my problem is that i am not getting spark. Where should i look next?

 

See post #4.

 

I did that once but can always go out and try and clean them again. Don't really have any electronics cleaner but went and cleaned up the prongs and springy things the best i could. What kind of volts should i get at the icu spring things when i have the ignition key turned on? Is there a good way to test to see if the coil is good.

 

I think he means post 3, your cps is shot...

 

I just put in a new cps that i got from napa. According to his post about testing the cps, i have the amount of volts coming out of it that it should.

 

My bad I thought the post said 5 not .5....carry on...nothing to see hear nut someone that can't read...

 

Not a problem. I had to look at it a couple times as well to make sure i was reading it right.

 

Started tracing things down and i have got 12 volts going all the way to the cap. Do you guys think i should do new cap, rotor and plugs, and maybe wires? Is there a way to test the wires to see if they are any good? I looked at the coil wire and where it attached to the cap it was all nasty and corroded inside. So i grabbed one i had laying around just to see if anything would happen with 12 volts going to the distributor.

Also, i just seen that there is a relay that is up under the little shelf that the coolant reservor sits on. Can anyone tell me what this relay mite be for?

Any other tips to try to get this think started?

 

Yhe fatter yellow wire at A should have 12 volts with ignition on.

 

Are you talking about at the icu or relay?

 

are you talking about at the icu or relay?

icu

 

Well i still don't have a running jeep. Here is the run down of what i have done or replaced so far. Have replaced the ignition switch, cps, fusible links that burnt, cap, rotor, plugs, plug wires, and the coil. I am getting 12 volts to the springy parts on the icu. Does anybody have any other ideas? Still doesn't seem like i am getting spark. We took a plug out and put one of the spark plug wires on it and layed it on a part of the motor to see if it would spark and it didn't. This is starting to drive me nuts cause i can't figure out what could be making it not start.

 

Laid it on the engine or made darn sure it was grounded?

 

We layed it on the valve cover, up against block, other places on motor

 

Would having a bad idle air control cause it the jeep to not start and not have spark? My iac is messed up so it wasn't getting a good connection.

 

Nope.

CPS has to generate a signal to the ECU. The ECU then fires the ICU. The ICU energizes the coil which sends a spark to the distributor cap through the coil wire. The spark travels down through the distributor cap to the rotor which carries spark to the outer terminals of the distributor cap, through the plug wires, to the spark plugs.

 

Well we went out to the junkyard today and got some parts for the jeep. Ended up getting a really good looking iac and also picked up a different ecu out of another renix jeep. Was told that the short may have fried the ecu as well. Of course like everything else i have done to this jeep, that didn't change anything and its still not running. I am just about done with throwing money at this thing and still not have a running jeep. Anybody got any other ideas? I went yesterday and checked all the grounds and cleaned them all up. Have done what everyone has told me and i still can't get it to run.

 

See if you have battery voltage to the #30 terminal of the fuel pump relay. That same circuit powers the ECU at terminal B7.