ecu help on 89 4.0

I have an 89 4.0 auto. The xj did not run when I received it. It came with multiple electronic parts one being a second computer (ecu). I am trying to identify which is the correct ecu for this particular rig. Is there anyway to find out which one is needed for this. I know they are different because numbers on them are different. Any help is appreciated.

89 4.0 auto should have come with ecu #53005428
man trans would have been #53005429, although they'll run and drive with either.
what number ecu's do you have?

Hellbent said:

89 4.0 auto should have come with ecu #53005428
man trans would have been #53005429, although they'll run and drive with either.
what number ecu's do you have?

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Correct^^. And, it will run with any 87 to 90 eCU.

Thanks for the info guys. Didn't know if they were ecu specific or not. I've got a no start issue and trying to figure it out yes cps has been replaced along with wires checked. I get power out of coil and into distributor but no spark on any wires cap rotor wires and plugs are all new. I'll check which ecu's I have and let you guys know for sure on that.

Ok the two I have are neither number the number on one is EF 8953005406. Other one is S 101140203 B this one also has this number on it 56006078

BenBru23 said:

Ok the two I have are neither number the number on one is EF 8953005406. Other one is S 101140203 B this one also has this number on it 56006078

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If the ECU plugs in, it will start the Jeep.

What's your CPS AC output voltage?

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 to 3/8” from the stock 5/16”, 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 01-26-2013

Thanks for the info cruiser54 I did do the resistance test and it was good I'll check ac volts tomorrow. I also found out this is not original motor but it does have the temp sensor at the rear of the head like the older 4.0 so I'm not thinking its an HO. This thing looks like a wiring mess I'm going to also check grounds is there any specific ones I should look at.

Click on the link below and visit Tips 1,3,4, and 5.
http://www.naxja.org/forum/showthread.php?t=1115935

Downloaded that last night lol lots of good info

BenBru23 said:

Downloaded that last night lol lots of good info

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Time to get to work, eh? LOL.

Note from DJ
This information may help you identify what the previous owner swapped into your Jeep
Block casting number location can be found hear in post # 2 by CJ7-Tim
http://www.jeepforum.com/forum/f11/4-0l-serial-number-location-995174/

Head casting number by years
It is easy to determine what head you have. On the driver’s side, about halfway down the cylinder head between #3 & #4 fuel injector but below the valve cover clean the lip of the head with a rag or solvent if really greasy. With a good light, you can read the casting number of the head.

Head casting number by years
Casting numbers are as follows:
Year............Casting No
1987-90......2686
1991-95......7120
1996-99......0630
2000-01......0331

Post back what you discover.

Ok I have a 91-95 head anything I need to know about this change going in an 89?

Also pulled cps and reamed the top hole to a 3/8th in. Hole and pushed it as far towards flywheel as possible and this is a rookie question but where it is mounted there is no opening to feel gears or anything on flywheel now if you move towards the rear of that same area there is an opening but no gear does the cps read through a layer of aluminum to pick up flywheel?

BenBru23 said:

Ok I have a 91-95 head anything I need to know about this change going in an 89?

Also pulled cps and reamed the top hole to a 3/8th in. Hole and pushed it as far towards flywheel as possible and this is a rookie question but where it is mounted there is no opening to feel gears or anything on flywheel now if you move towards the rear of that same area there is an opening but no gear does the cps read through a layer of aluminum to pick up flywheel?

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This:

Cruiser’s HO into Renix Swap

This swap is easier than some will lead you to believe, generally those who have never done it. Those of us who have done it, like myself, will share with you the things that need to be done for a successful swap. Just think of it as swapping in a long block.

The HO and Renix have some differences but none that can’t be overcome very easily.

Any HO engine from an XJ or ZJ through 1999 can be used. One running change was that the rear of the head was no longer drilled and tapped for the temperature gauge sender beginning in the 96 model year. The sender can be relocated to the threaded hole in the thermostat housing taken from the HO engine. You’ll have to extend the wire to that location. Some brave souls even drill and tap the HO head for the sender.

You will be using the intake and exhaust manifolds from your Renix, along with all your sensors and wiring. Since the intake ports of the HO are slightly different, you use the Renix gasket. Exhaust ports are identical.
You will need to use your Renix distributor as it is different than the HO because they use different fuel management systems. The flywheel or flexplate from the Renix must be used so your CPS gets the correct signals. The valve cover from the Renix allows you to keep your CCV system intact and requires no modifications.

The HO block will have a plug in the coolant galley on the driver’s side of the block, closest to the front, which needs to be removed so your Coolant Temp Sensor can be installed in it’s place just as it is on the Renix. It requires a 5/16” square drive or a modified 3/8” drive that has been ground down to fit. Do this before installing the engine.

As for the knock sensor, which is located just above the oil pan on the driver’s side of the engine about mid way, all the blocks I’ve seen are threaded for it. If not, I’ve heard they may be drilled but not tapped. Tap the hole if that’s the case.


Revised 03/28/13

Ok so tell me this when did the HO motor start? I'm goin to parts store now to pick up a new distributor because when I crank it over it seems like the rotor is pushing against the cap to much as it looks like the center is wallering around I'm going to buy one for an 89.

91 was first year for HO. 87 to 90 dizzies were virtually the same from year to year.

Ok put the correct distributor with cap and rotor still no spark I'm picking up a new cps from Napa tomorrow and will install either tomorrow night or Saturday and fill you all in

New cps from Napa still no spark.... Does the distributor ground itself to the block? And also could the main wiring connector at the firewall be the possible issue?

BenBru23 said:

New cps from Napa still no spark.... Does the distributor ground itself to the block? And also could the main wiring connector at the firewall be the possible issue?

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Distributor doesn't NEED to ground to the block. I'd be doing some testing or practical suggestions related to these issues.

Test the CPS, Clean the coil contacts to the ICM.