No Spark (was Starter Solenoid wiring)

[LoTGoD]

I've checked the online manuals that I found, but can't quite make sense of it.

 

It figures this was the one thing that I can't remember when I went to hook the wiring harness back up.

 

90 MJ 4.0L Renix

Getting fuel to the rail

Getting ~9.6 volts to the dizzy

It appears the coil pack is not sending out power to the dizzy, as no spark on cranking it over

 

I have all ring terminal wires hooked up to the center post of the solenoid

 

I have a group of 3 wires (black with white stripe, orage, and green) with single connectors that I assume go to the solenoid

Also have a single green wire with single connector from another group of wires.

 

Per my pic, there are 4 single connectors on the solenoid. I know they were hooked up wrong, as the black wire with the white stripe started smoking VERY badly when I hit the ignition. If you can tell me what that wire is, and where it goes, I'll trace it out and replace it from my bad harness.

 

 

If you could tell me where they are connected on your Renix motor, I would sincerely appreciate it. Bonus points if you can tell me what each wire is. I'm going to look at the 88electrical manual that Genovast posted, again, and see if I can find it in there.

 

Thanks again!

 

Aaron

[LoTGoD]

After messing around with it for the last 3 hours, I still have no spark.

 

Can anyone tell me which of the 4 wires that run to the coil provide power? I have 12v to one yellow wire, but I am assuming that once the ignition is triggered, there should be another wire that sends juice to the coil?

 

I'm pretty sure I have all 4 wires plugged in to the starter solenoid correctly now.

 

Man....after all this work, it sure is frustrating not hearing the old heap run. :headpop: :headpop:

[maddzz1]

I'm at work but I can check it a little later if you still don't have it running. You said the black wire started smoking, since those are fusible links maybe one of them got fried.

[LoTGoD]

I'm at work but I can check it a little later if you still don't have it running. You said the black wire started smoking, since those are fusible links maybe one of them got fried.

 

I traced the black wire to a cluster of ground wires, so I am assuming I put power to it and caused a short, which melted some coating on the wires.

 

There is still flow through the wire, as verified with a test light on the positive terminal of that battery.

 

My next assumption is that I have a bad CPS, or a bad CPS connection. After searching much on "no spark" it appears a bad CPS could cause this.

 

Would having installed the incorrect flywheel still allow the CPS to send signal for spark? My assumptions on this is that even with the wrong flywheel, the CPS will still send a signal, albeit the wrong one?

 

Plan for tomorrow is to clean CPS connection with contact cleaner, and retry. If that fails, I'll try this bit that I found on JU:

 

CRANKSHAFT SENSOR TESTING PROCECURE: 1987 – 1990 4.0 L engines

 

Test # 1

 

Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the sensor and measure across the connector's A & B leads. Your meter should show a resistance of between 125 - 275 ohms. If the reading is out of range, replace sensor.

 

 

Test # 2

 

You'll need a helper for this one. Set the volt/ohm meter to read 0 - 5 AC volts or the closest AC Volts scale your meter has to this range. Measure across the CPS leads for voltage generated as your helper cranks the engine. (The engine can't fire up without the CPS connected but watch for moving parts just the same!) The meter should show .5 - .8 VAC when cranking. If it's below

.5 VAC, replace sensor.

 

Does this make sense to those that have had this issue?

 

All starter solenoid issues have been resolved.

[HOrnbrod]

The Renix flywheel has notches all around it, not just the three wide ones 120° apart and the following three or four found on the 91 and up H.O. flywheels and flexplates. The Renix CPS is an induction coil, not a switch. It also serves as an rpm signal, hence the notches all around the flywheel. It creates a square wave pulse that the computer uses to time the ignition pulses to the coil. The H.O. CPS is a Hall Effect (magnetic) switch that creates a similar square wave signal, but in a different way; magnetic pulses rising and falling based on the flywheel notch spacing to create a pseudo-square wave.

 

The wrong flywheel could ( but not likely) mess up the CPS in either case. And you'll have some kind of CPS output signal w. the mismatched components, but of course not the correct square wave for the computer to read. Do your CPS resistance and voltage checks and see what happens, but these tests are not always conclusive. I hope your computer isn't damaged.

[LoTGoD]

Well...its been a long night.

 

First, I verified that I did install the Renix flywheel, as the other one that I have in the garage is notched 120° as per Hornbrod's description.

 

Next, I tested the CPS per the instructions. My multimeter must have been acting up, because I got no reading, even from the new one. I figured I might as well install the new one. Took about 30 minutes and 3 feet of extensions, and I got it in.

 

Still no spark.

 

Tested the coil by taking to a buddy's MJ and installing it. His MJ fired right up.

 

Looks like the wiring harness swap is going to be the culprit. The plan is to tear the harness back out and make sure I didn't miss any connections.

 

Anyone have any other ideas?

[Wildman]

Yea........with the wrong wire (ground wire) being hooked up to the starter relay, pull the ECU out and open the case, check for any burnt resistors on the circuit board.

 

Also.......double check and add if needed a ground wire from the ECU mount plate to the engine ground stud (where the battery ground attaches)

 

You really need to double check the Ohm's on the CPS, even if you get a cheap $3 volt meter just for this test.

 

I know your :fs1: But, a few simple checks might be worth it before you tear out the wiring harness :D

[LoTGoD]

Thanks for those suggestions Wildman!

 

I guess that will be the start of the testing tonight.

 

Per your suggestion of testing the OHM's...we are talking about testing across the lead wires of the sensor itself...the male leads that come out of the bellhousing, right? The reason my tester was acting up is that the wire broke off the positive contact point, so I am left with just a bare wire to hook it up. I'll buy some new test leads tonight and see if that makes a difference.

 

Once I pull the ECU and check, if it is bad, I do have a spare to hook up. Shouldn't make a difference what year the ECU is from, as long as it is a Renix ECU? 87-90 should be interchangeable?

[Wildman]

Correct.........you check the CPS leads, from the sensor, across A & B....... Here, I chopped this from Mr. Eric Giordano = "Basic RENIX / non-HO Engine Sensor Diagnostics"

 

http://www.lunghd.com/Tech_Articles/Eng ... ostics.htm

 

 

.........Test#1 - Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the cps and measure across the CPS connector's A & B leads. Your meter should show a CPS resistance of between 125 - 275 ohms. If it's out of that range by much; replace it. (* - Note: HO engines are measured from the B & C connectors and should have near zero ohms.)..........

 

{Got to put credit when due, were it came from} :yes:

 

I should have a few spare ECU's, Their not all the same -

 

4.0 - '87-88 = Manual #5409 - Auto #5406

4.0 - '89-90 = Manual #5429 - Auto #5428

 

That's the last 4 numbers on the label (IE: 5400-5428)

 

I was just tossing out additional ideals for you, couldn't see you yanking out the harness, just check a couple things first.

 

As the immortal Mr. JT would say............K.I.S.S.

[LoTGoD]

Well...Ohm's read 221, so the sensor must be good.

 

I replaced the engine harness, and still got nothing.

 

My logic at this point leads me to believe I missed something that needs to be connected under the steering wheel for the ignition, as I am getting +14 volts at the coil with the key in the run position. Still no spark while it is cranking. Doesn't seem to be sending fuel in to the cylinders either.

 

Have a buddy with an 88 MJ that I am going to look under the dash and steering wheel tomorrow to see if anything jumps out at me.

[Wildman]

:hmm:

 

No spark and no fuel (meaning the injectors are not pulsing open) = problem with the ECU.

 

Take your volt meter, with the new leads, set on DC and touch a hot lead from the fuse panel, to the ECU base and see if you have a reading (12VDC)........meaning, see if the ECU is grounded before you pull it out (and I hope you have small hands to reach up behind the dash)

 

If you have voltage with the key on at the right hand tower and it cranks (starter engages) I wouldn't think you have a problem with the ignition switch or any thing at the steering column :dunno:

[HOrnbrod]

Ayup. Sounds like ECU mate.

[LoTGoD]

What a long weekend...

 

After trying Wildman's suggestions (I do have a solid ground at the ECU) I am still back to no spark and no fuel.

 

Both ECU's are #5429. I've opened both of them up, and there are no blown caps, no burn marks on the boards, nor are there any tell-tale signs of a power surge.

 

I've pulled all wiring out and replaced it with my old corroded harness that did fire the engine before all of this began.

 

I've decided that I must be overlooking something completely obvious at this point. I have to not be hooking something back up when I install the in-cab wiring, as the entire motor harness has everything connected.

 

What should I do? My thoughts were to head to a local yard and tear in to an XJ dash to see where everything is connected and duplicate that back on my end.

 

I'm feeling pretty helpless at this point, and have stopped all other parts of my build until I can get this corrected.

 

Any more help or direction is greatly appreciated.

 

Aaron

[Wildman]

Which ever harness your using, it's basically plug and play. I'm sure you realize this ;)

 

So, I hear your frustration on this.............

 

If you checked that the ECU had ground, the circuit board looked clean, with no burnt resistors, and no damage to the circuit lines, then it's on to the next solution.

 

One thing I would have done, before tearing out the harness, was to install the CPS bypass, where you wire the senor directly to the ECU (there was a Service Bulletin on this years ago)

 

We found this patch on an '88 that's giving up it's parts for other MJ's to live on, and Cherokee is the proud owner of this harness with the patch kit.

 

I can't find the FSB on this right now............But, You basically cut the 2 wires from the engine harness (the one from the injector feeds) to the CPS connector, drill a 1/4" hole thru the firewall, and install 2 new lead wires directly to the ECU at C1(18VT) and D1(18WT)

 

From the symptoms you write about, above, there a problem with the ECU letting the injectors open, and providing spark as needed :hmm:

 

Did you by chance pull the disturber??? Got the timing off??

 

Have you checked the Cam shaft Position Sensor???

 

http://www.lunghd.com/Tech_Articles/Eng ... Stator.htm

 

The only other idea I have, which I'm sure you done, was to use contact cleaner on every connector, check the leads at each connector, and applied Die-elect grease to each connector.

 

Stay in there..........I'm sure you'll get this problem solved.

 

But.........take a brake, walk away from it for a couple days. I've gotten more done with taking brakes, and thinking about things before just trying this and that, and tearing this out, and tossing that 20feet away :headpop:

[LoTGoD]

Which ever harness your using, it's basically plug and play. I'm sure you realize this ;)

I'm pretty sure I do, but there are subtle differences between the harness that Pat sent me, and my original 90 harness. some of the connectors on the engine side of the fuse block connector are different, requiring a different ECU/injector harness.

 

One thing I would have done, before tearing out the harness, was to install the CPS bypass, where you wire the senor directly to the ECU (there was a Service Bulletin on this years ago)

 

We found this patch on an '88 that's giving up it's parts for other MJ's to live on, and Cherokee is the proud owner of this harness with the patch kit.

 

I can't find the FSB on this right now............But, You basically cut the 2 wires from the engine harness (the one from the injector feeds) to the CPS connector, drill a 1/4" hole thru the firewall, and install 2 new lead wires directly to the ECU at C1(18VT) and D1(18WT)

 

I did see this on JU, but since the motor ran right before I pulled the original harness, I didn't feel that it was something that "had" to be done to get it to run right now.

 

Did you by chance pull the disturber??? Got the timing off??

Nope. I haven't touched anything mechanical with the engine since this build started. I feel that my downfall was pulling the harness 2 months ago, rather than waiting until the replacement unit arrived. You think you'll remember where everything connects...and then I see I have some "extra" wires that aren't connected, and can't remember if they were connected on the original harness or not.

 

I plan to get some pics of the ones that I don't have hooked up right now, in the hopes that someone will be able to tell me "Those need to go here..." or "Those aren't used in your application..."

 

Have you checked the Cam shaft Position Sensor???

 

http://www.lunghd.com/Tech_Articles/Eng ... Stator.htm

 

Haven't done this yet, as I am not getting spark out of the coil at all, so I figured this wouldn't be applicable.

 

The only other idea I have, which I'm sure you done, was to use contact cleaner on every connector, check the leads at each connector, and applied Die-elect grease to each connector.

This is the next step. I've cleaned all contacts. Used grease sparingly on those circuits that I felt were the direct cause of the problem.

 

Stay in there..........I'm sure you'll get this problem solved.

 

But.........take a brake, walk away from it for a couple days. I've gotten more done with taking brakes, and thinking about things before just trying this and that, and tearing this out, and tossing that 20feet away :headpop:

I haven't really done anything substantial since last Thursday. It was a nice break over the weekend, but in the end, all I really did was sit around thinking about what the problem might be.

 

I think I mentioned this previously, but I have a friend with an 88 MJ that I am going to ask to borrow for an evening. Plan to pull his lower dash stuff out and see if I can see anything on his that doesn't look like mine, connection-wise.

 

Thanks for all the help so far, and the nice words of encouragement!

 

Aaron

[Wildman]

Yes........I remember the "problems" you had getting the harness............ :roll:

 

Isn't that a sticky now :hmm:

 

OK.......what did the donor harness come out of........an XJ???

 

I'm just tossing out ideas to you, the problem is...........you are here (X), and I'm over here(X)

 

Yes, if you have a MJ near by, that you can "borrow" then you can do the ole track down each connector that is used, or not used, as you know, the harnesses come with many options that are either used on your MJ, or not, IE: cruse control.......

 

Ask Cherokee how many times he's swung over to check out this and that, and one time when I stopped at his place, 5 minutes latter, he had my hood open, checking the routing of this and that.

 

I toss that CamPS out, that's another senor that can cause "no spark"

[LoTGoD]

OK.......what did the donor harness come out of........an XJ???

 

According to the original exchange between Pat and myself, it came out of an 89 MJ.

 

Yes, if you have a MJ near by, that you can "borrow" then you can do the ole track down each connector that is used, or not used, as you know, the harnesses come with many options that are either used on your MJ, or not, IE: cruse control.......

 

Yep, new guy on here that bought an MJ and live about 5 minutes from me. His is an 88 I think, that was manual, but was converted to an auto. It can't hurt to look.

 

I toss that CamPS out, that's another senor that can cause "no spark"

But with my no fuel issue, wouldn't it make more sense that it is something else at this point? I'm not doubting your motives, just assuming that it is my lack of remembering where [X] connectors went on the install of the new harness.

 

Since all else has failed at this point, I'm just going to do more thinking and research before I move any further. Want to make sure it isn't the obvious thing now, then move on to the CamPS.

 

Man this is frustrating.... :headpop:

[Wildman]

OK........I re-read everything that was posted so far..........

 

The only difference you will find between the '89 harness and the '88 harness is the C101 connector, that was eliminated in '89-90. That's the connector that comes from the ECU to the engine (Injector) harness.

 

I'm sitting here reading the '88 electrical troubleshooting manual for the MJ :idea:

 

What I do see is...........3 Fusible Links that come off the starter relay (near the right shock tower) If some one were to put a ground wire on the relay post, by mistake........Then the fusible links should be tested, and maybe possibly even replace the starter relay. The starter relay is not just for closing a circuit for the starter solenoid, it also sends a open signal to the shock tower.

 

The 3 fusible links are the relays on the shock tower, B+ Latch, Fuel Pump, O2 pre-heater.

 

I'd start there first, checking the fusible links, and the relays.

 

I tossed out the CamPS this morning, thinking you don't have spark, but then you reminded me that you also don't have fuel :hmm:

[JeepcoMJ]

89 5 speed mj is what the harness came out of.

 

IIRC the build date on it was early 89. I got the MJ from geonovast...he still has the title for it so he could confirm the year.

 

I'd have to agree that a ground being plugged to the starter relay could fry out the starter relay and/or fusible links.

 

did you get it plugged in, or with everything unplugged? I cannot remember.

 

-Pat

[LoTGoD]

What I do see is...........3 Fusible Links that come off the starter relay (near the right shock tower) If some one were to put a ground wire on the relay post, by mistake........Then the fusible links should be tested, and maybe possibly even replace the starter relay. The starter relay is not just for closing a circuit for the starter solenoid, it also sends a open signal to the shock tower.

 

Fusible links would feel "mushy" if they were fried, correct? If so, I've check them all, and they feel solid. Will test for continuity tomorrow.

 

Started relay was swapped with my friend's 88 tonight. Mine started his, his didn't start mine.

 

did you get it plugged in, or with everything unplugged? I cannot remember.

Pretty much everything was connected. All links looked good. Will check for current flow tomorrow.

 

 

Had buddy's 88 MJ over tonight and double checked in-cab connections. All sync with mine. My dad suggested the CAMshaft Position Sensor, but since there is no injector pulse, should I bother with that at this point?

 

Tested injector wiring during crank, and no voltage present at injector wiring connection.

 

I'm beyond frustrated at this point, and have ended up laughing each time I try and crank it :yes:

 

Not sure what next steps to take....

[Wildman]

The CamPS is a quick test, you really don't need to remove anything.

 

Here......if I didn't link it -

 

http://www.lunghd.com/Tech_Articles/Eng ... Stator.htm

 

A 'quick' check of the fusible links is just pull on them........if then pull apart......you know there no good..........other wise, still do a continuity test.

 

Well.......you took the starter relay out of the equation :thumbsup: