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Ok im stumped

NW-ZJ-SCOTT

NW-ZJ-SCOTT

TEXAS-JT-SCOTT
NAXJA Member
Location
NE Texas
I was cruisin home from wheelin, and the jeep died. I towed it home. and have been trying to diagnose the issue ever since, its been a week now.

I replaced the Crankshaft position sensor
I changed out the Coil with one out of another jeep, and vice versa. so i know my coil is not bad
Checked the Throttle position sensor

I have no spark. nothin comin off the Coil. Could it be the ECM?
all my fuses are good.

It cranks over. but no fire.
 
Check the ground that mounts right where the dip stick mounting bolt is for the motor oil, If its loose of isnt a clean conection you will get all of those symptoms.. :thumbup:

could also be the auto shutdown relay
​
 
Sounds like your distributor threw the magnetic pickup inside the cap. Easy check is to undo the two bolts and see if everything in there still looks ok. If not its probably to mangled to fix and you will need a new one.
 
There is no spark coming off the coil. so it cant be the pickup inside.

the cap/rotor/plugs/wires are all new (within the last 1500m)

im gonna check my grounds tomorow, where is this "Auto shutdown relay" located?
 
in the engine bay fuse box if memory serves.
labelled as ASD Relay, have a look see.
 
j33pownr said:
Sounds like your distributor threw the magnetic pickup inside the cap. Easy check is to undo the two bolts and see if everything in there still looks ok. If not its probably to mangled to fix and you will need a new one.
Click to expand...

This will not stop it from running. It will still run with it disconnected, though it will take a few seconds longer to start as the ECM waits for a signal, if it doesn't get one it randomly selects a cylinder to start with. Also referred to as a cam sensor.
 
89CherokeePioneer said:
This will not stop it from running. It will still run with it disconnected, though it will take a few seconds longer to start as the ECM waits for a signal, if it doesn't get one it randomly selects a cylinder to start with. Also referred to as a cam sensor.
Click to expand...

Oddly enough, it stopped mine from running. Being that it's tied into the ASD relay(at least on my 96, and probably newer models), just like the CPS. The coil pickup is a hall effect sensor just like the CPS, and if it fails you will have no spark and no fuel injectors firing. YMMV.
 
How far along in the thread do we get before anyone asks for specifics on the problem vehicle?

:twak:

Y'all remind me of a buncha Boeing engineers.
 
Dave41079 said:
Oddly enough, it stopped mine from running. Being that it's tied into the ASD relay(at least on my 96, and probably newer models), just like the CPS. The coil pickup is a hall effect sensor just like the CPS, and if it fails you will have no spark and no fuel injectors firing. YMMV.
Click to expand...

Maybe it does on the later years? I assumed it was an 89. Don't ask why, he didn't mention it
 
Looks like we lost the OP. But we should have a requirement that all vehicle stats are required by the OP to ask a question!:hang:
We are chasing our tails otherwize.:sure:
 
90Blue_XJ said:
Looks like we lost the OP. But we should have a requirement that all vehicle stats are required by the OP to ask a question!:hang:
We are chasing our tails otherwize.:sure:
Click to expand...

We're chasing our tails trying to get them to do that in the first place. :yelclap:
 
ECKSJAY said:
We're chasing our tails trying to get them to do that in the first place. :yelclap:
Click to expand...

I am on another forum as well and they have a drop down menu under the posters screen name and avatar that tells what vehicle we are trying to get fixed. That saves everyone a lot of time and confusion. Naxja could add that and solve this on going problem. I have been on this forum for about 4-5 years and have seen so many wasted posts b/c people don't post up what their specs are when they ask a question.
 
89CherokeePioneer said:
Maybe it does on the later years? I assumed it was an 89. Don't ask why, he didn't mention it
Click to expand...

It says that on his profile.
 
haha you didnt lose the OP, i lost the Thread!

Its an 89 Pioneer. renix 4.0
Dont have a dime to my name so i have to wait till friday, but so far im checking the Fuse's and ground..
 
Nobody's mentioned the MAP yet.

Don't completely trust the CPS yet, even if new. On the very rare occasion, they are bad out of the box. Just something to keep in the back of your mind when you start going back around again the second time. Hope that doesn't happen.
 
UPDATE:

Jeep was parked in a town 40 miles from my home. after 10 days of trying to fix it. I got it towed home. three cherokees rollin downtown Portland on a friday night. wow that was fun..

SO, Tech update:
I have checked the grounds.. all tight
Im putting in a new battery and cable, doubt this will help but needs done

I checked all 4 of the relays under the hood (renix system)
The 3rd one closest to the grill Has a rattle. It seems to be the Fuel pump relay. HERES WHERE I NEED HELP.
is the Fuel pump relay tied into the system? I cant figure out why i dont have spark?
Chiltons shows a graph and it seems to be tied in with the system. so im thinkin if its bad, the ecm is recognizing this and im not getting fuel OR spark.

my jeep has been down for 12 days. I really need your guys help.
Im new to the Jeep stuff, and this forum has been a great help, i have learned this is my #1 Trusted source for Help and Can completely see the Value in Joining the "Red" team..
 
Swap it with the A/C relay. They're the same. Relays do go bad on occasion. What usually happens is the circuit they activate doesn't get the proper signal from the controlling sensor, so they don't engage.

IIRC the Renix ( and I will get corrected if wrong,) you have to have all the sensor inputs to activate the coil. If there is no "Camshaft" input from the distributer, the computer can fudge that, but the rest are mandatory.

Check that MAP - it needs both vacuum from the intake, and voltage from the harness to send a signal to the computer.
 
I am pretty sure Renix can start ( meaning you get fuel and spark) with only one working or attached sensor, the CPS. The MAT or IAC sensor when bad, can make it real hard to start (flooding), but you would get fuel and spark with all sensors disconnected except the CPS.

I have started my 87 Renix, 4.0 with the CTS, TPS, MAP, O2 and IAC all disconnected.
 
Last edited:
ok, bought an ohm meter, the CPS gets 0.23 constant..
Thats "cold" tho.. the book says 125-200 HOT..

Also, will unplugging the ecu and plugging it back in Help? Its a bitch!
 
Was the CPS still connected to the wiring harness? If so disconnect it, and retest it. If it was disconnected then it is bad, shorted out.
 
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