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No spark from ignition coil?

Tiny
JEEPSTER94
  • MEMBER
  • 1994 JEEP WRANGLER
  • 127,000 MILES
I have a 1994 jeep wrangler 2.5 liter that has no spark from the ignition coil. I have changed the coil and the crank positioning sensor. There is no to very little power going into the coil. I changed a fuse and it went from 0 volts to 2.3 volts. The jeep has been sitting for a few months so there may be some corrosion buildup. Thank you for your help I really need it
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Friday, August 23rd, 2013 AT 2:07 PM

32 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 33,912 POSTS
2.3 volts suggests the automatic shutdown (ASD) relay is turning on but that there's a high-resistance connection somewhere, so lets check that circuit first. Remove the ASD relay, jump terminals 30 and 87 together in the socket, then read the voltage at the ignition coil or any injector.

Here is a guide to help test the relay and the ASD location as well below.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

This guide can help as well

https://www.2carpros.com/articles/how-to-test-an-ignition-system

Check out the diagrams (Below). Please let us know what you find.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
CARADIODOC
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There is two parts to the circuit. Since you had 12 volts to the ignition coil when you jumped the ASD relay, we know the high-current half is working and the fuse is okay. If you do not even see that 12 volts switch on with the relay installed for that first one second, that points to an Engine Computer problem or a different blown fuse. Engine Computers do not fail on Chrysler products very often. If you have a service manual and know how to read the wiring diagrams, there will usually be three or four 12 volts supplies feeding the Engine Computer that you need to check. One will be there all the time; one will be switched on through the ignition switch, and one will come through the ASD relay.

Before we go looking for difficult stuff, did you check that voltage with a test light or a voltmeter? If you used a voltmeter and did not see 12 volts for one second after turning on the ignition switch, check it again with a test light. Most voltmeters do not respond fast enough to catch that one-second blip.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
JEEPSTER94
  • MEMBER
  • 7 POSTS
I used a voltmeter but I do not have a 12 volt test light. I pulled the cap off of the relay and it does not move when the engine is cranked. I get fuel up to the fuel bar but I do not know how to test the injectors.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
CARADIODOC
  • MECHANIC
  • 33,912 POSTS
What is of most importance is does that relay click on for one second when the ignition switch is turned on. If it does not, there is a problem in the circuit that controls it. If it does, there is a problem with the cam or crank sensor.

Here is a guide to help test the injectors

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Please run down this guide and report back.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
JEEPSTER94
  • MEMBER
  • 7 POSTS
It does not click.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
JEEPSTER94
  • MEMBER
  • 7 POSTS
I have checked all my fuses I have power to all but the accessories LPS fuse. I changed it but still no power.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
CARADIODOC
  • MECHANIC
  • 33,912 POSTS
You need to check right at the Engine Computer. I have a real lot of Chrysler service manuals but the closest I can find for yours is for a 1993 Grand Cherokee, and that did not have the 2.5L engine. Chrysler was pretty consistent though with their wiring from year to year and with different engine sizes so let me see if this looks right.

They show terminal 3 as a pink/black wire with full battery voltage all the time for both the 4.0L and 5.2L engines. Terminal 9 is a light blue or a light blue/red wire that gets 12 volts from the ignition switch when it's in "run". You can remove the 60-pin connector and measure right on the terminals, but do not stick a meter probe in too far as that could stretch the terminals.

Next, there are multiple power ground wires to check. You can use an ohm meter to measure the continuity but a more accurate test is to remove the connector's rear cover, then back-probe the terminals through the rubber seal and measure voltage while the connector is plugged in and the ignition switch is on. Typically you can expect to find as much as 0.2 volts but more than that indicates a high-resistance connection. Terminals 5, 11, and 12 are all grounds and are all black/tan.

All of these wires are in one of the outer of the three rows of terminals, (assuming you have the common 60-pin connector, and not the newer style three smaller connectors). One row has terminals 1 - 20.

I should have you check something easier before I jump the gun and head to the computer. There is four terminals on the ASD relay socket. You already jumped the two high-current terminals. Look at the other two that are on the sides and parallel to each other. One of those should get 12 volts all the time the ignition switch is in "run". Make sure that is showing up.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
JEEPSTER94
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There is no power to the other two terminals.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
CARADIODOC
  • MECHANIC
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Terminal 30 or 87 should have 12 volts all the time. We established he's there because you jumped those terminals and had 12 volts at the ignition coil. Of those two parallel terminals on the sides, one gets grounded by the computer to activate the relay and one gets 12 volts from the ignition switch.

I do not know what they used for an ignition switch but if it is the same one Chrysler used in the early 1990's, check that and its connector for signs of overheating and melting. Typically two terminals will be blackened and the connector body will be melted around them.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
JAYBOS10
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  • 8 POSTS
What do you mean by ignition switch? On the steering wheel? I am at this point with no power at the other two points on the ASD. And stuck.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
CARADIODOC
  • MECHANIC
  • 33,912 POSTS
The ignition switch is what you turn with the key. That supplies the 12 volts to one side of the coil in the ASD relay. The Engine Computer grounds the other terminal to turn the relay on, first for one second when the ignition switch is turned on, then again when the engine is rotating, (cranking or running), and it knows that by the signal pulses it receives from the crankshaft position sensor and the camshaft position sensor.

Two terminals on the ignition switch's connector and one set of contacts inside the switch commonly overheat and become burned and pitted, and the heat generated by one of them migrates out to the other part and causes the same damage. That part of the switch almost always is for the accessory circuit, so when it develops that problem, you will have no radio, power windows, and heater fan. The engine will still start and run normally. This happens most often to people who leave the fan set on the highest speed when they turn the ignition switch on and off. This switch problem rarely affects the low-current circuit that feeds the ASD relay, but it is one of the places we have to check for with this problem.

You should really start a new question specific to your vehicle so the other experts will see it and have a chance to reply. Here, only the two of us will be notified when an update has been posted. That may not get you the most help we can give you. Please be sure to list the engine size, mileage, and transmission type so our answers will be more relevant. List the diagnostic fault codes if you found any related to the problem, and include all the things you tested already, and the results.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
JAYBOS10
  • MEMBER
  • 8 POSTS
It worked I now have power to the coil and the engine started I love this site. The ASD relay cost me $33.00
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
CARADIODOC
  • MECHANIC
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Nice work, we are here to help, please use 2CarPros anytime.
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Thursday, January 17th, 2019 AT 2:59 PM
Tiny
MHOLT59
  • MEMBER
  • 1 POST
  • 1994 JEEP WRANGLER
  • 2.5L
  • 4 CYL
  • 4WD
  • MANUAL
  • 200,000 MILES
The other engine blew up so I have put another one in.
When the other engine expired every thing worked great, then the vehicle has sat for about eight months I have put the engine in I used my distributor, coil, everything, the engine will crank over but will not fire.
I tested the CPS it checked good so did the cam positioning switch.
I read on a thread someone with the same problem, so took out the ASD circuit and jumped 30 and 87 and got twelve volts to the coil and injectors.
Put it back in and when I cut the switch on I have one second of power on the injectors when I try to crank it no pulse I really could use some help.
Thanks
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Saturday, September 26th, 2020 AT 12:48 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,912 POSTS
The fact the ASD relay turns on for one second when you turn on the ignition switch proves that circuit is okay and the Engine Computer has control over it. Next, it needs to turn on again during engine rotation, (cranking or running), and the computer knows that by the signal pulses it receives from the crankshaft position sensor and the camshaft position sensor. One of those two is not working.

The cam sensor is in the distributor, so among other things, be sure the shaft is turning during cranking.

The place to start is by reading and recording any diagnostic fault codes, but codes for these sensors often do not set just from cranking the engine. They typically need more time to set, as when a stalled engine is coasting to a stop. Regardless, Chrysler made reading fault codes yourself much easier than any other manufacturer. Cycle the ignition switch from "off" to "run" three times within five seconds, without cranking the engine. Leave it in "run", then count the flashes of the Check Engine light. You can go here:

https://www.2carpros.com/articles/retrieve-trouble-codes-for-chrysler-dodge-plymouth-odb1-1995-and-earlier-car-mini-van-and-light-trucks

for a better description of counting the flashes, and to see the definitions, or I can interpret them for you.

There is no way to test these two sensors without special equipment that no shop has. Instead, use a scanner to view live data. I have a Chrysler DRB3 for all of my vehicles. On that one, both sensors are listed with a "No" or "Present" during cranking to show if the signals are showing up. When one is listed with a "No", the sensor itself is defective only about half of the time. We also have to look at wiring and connector terminals, and for mechanical problems related to those sensors. Aftermarket scanners will have a similar way of viewing those sensors.
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Saturday, September 26th, 2020 AT 12:48 PM (Merged)
Tiny
TIAMARNAS
  • MEMBER
  • 1 POST
  • 1992 JEEP WRANGLER
  • 2.5L
  • 4WD
  • 104 MILES
How do I best repair a open circuit, or asd relay the relay is new
I changed out the whole ignition system still no power to distributor
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Saturday, September 26th, 2020 AT 12:49 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
If it's an open circuit it means that a wire is broken or power is not being transmitted from one place to another so you have to trace the circuit. First see if you have spark at dist main wire I've included which wires to check to see if asd is getting power and which fuse to check I've also included a tip by one of our people which causes the no spark condition. And which fuse to check because it blows it.
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Saturday, September 26th, 2020 AT 12:49 PM (Merged)
Tiny
CKELLEY1
  • MEMBER
  • 1 POST
  • 1992 JEEP WRANGLER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 139,997 MILES
Will not start! Fairly new engine installed recently new crank sensor, new pickup distrib, new computer, new cap, new wires, new roter what else can we do?
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Saturday, September 26th, 2020 AT 12:49 PM (Merged)
Tiny
BREWER
  • MEMBER
  • 34 POSTS
How do you know you have no spark? Are you certain this is the problem or could it be something else not causing the vehicle to start?

Did you prime the engine? Do you have oil pressure? Did you open up the engine to do that crank sensor? Not positive about that sensors location is all. I have a 4 cyl not a 6.

Couple things to check - depending on how long it took you to fix everything. If you took the oil pan off to work on the crank. Did you disturb the oil pump? It might need to be primed up again. To do this, crank the engine with the plug wires. Unplugged - until you get oil pressure reading on the gauge. (Or you can pull the distributor and using a long flathead screwdriver in the hole, spin the oil pump counter clockwise for about 5 mins with a corder power drill - to remove the air from the oil system, and prime the pump)

The next thing it might be - depending on how long the repair work took you. Oil in the cylinders? If the repair work took a long time, then it is possible the oil slowly dripped and dried out in the cylinders. To fix this, you need to squirt some oil into the cylinders at the spark plug holes. (Not a lot, just enough to lube the cylinder walls) work the cylinders up and down manually - by hand cranking the engine a few times. This should restore compression to the cylinders. Although before you go to that effort - check the compression using a gauge on each cylinder. It might only be one of them, or none at all.

After all that - I would double check the ground wires for those new components - it's an old jeep - probably has some dirty / rusty components under that hood - mine does. Verify all the contacts are good.

(Oh and this is really a long shot but happened to me. Check the ground wire from the battery to the nearby firewall. The bolt for mine was rusty and wiggling the wire got mine to run. Turned out for me to just be a faulty ground wire)
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Saturday, September 26th, 2020 AT 12:49 PM (Merged)
Tiny
JUNKER 81
  • MEMBER
  • 2 POSTS
  • 1990 JEEP WRANGLER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
I just changed motor in my wrangler. I started it it ran fine for about 10 min. And died. There is no spark coming out of main coil wilre. The pick up is good in the dist. The coil is good, the ignintion control is good, I checked all fuses under dash they are good. What should I be checking now?
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Saturday, September 26th, 2020 AT 12:49 PM (Merged)

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