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need help ASAP please! no power to coil

1031 Views 17 Replies 6 Participants Last post by  89Saharagreen
ok guys im on the verge of rolling her down the hill
i can not get no power to the coil
i replaced the CPS and im getting a bouncing tach
so thats telling me the CPS is working
im getting no codes
the haynes manual is giving me no help
please i need some help
91 yj FI 2.5
thx farmer
1 - 18 of 18 Posts
So you know that spark isn't coming out of the coil, you checked it at the coil, not at a plug wire? if the coil is getting power make sure the ground is good. make sure you have fuel pressure and injector pulse, you might have more than one thing not working. if you don't have pulse and spark, you could have a cam sensor, or ecu problem.
No Power To Coil
i have fuel just no power to coil
thx farmer
ECU is prolly fried. Did you check the fuses and relay for the Ign. control module?
how can u troubleshoot the ECU to see if its toast?
thx farmer
Would like to see a simple troubleshooting no-start chart for our YJ's.
anyone?
jeeps dead need some help
thx farmer
Text Diagram Line Design Font


This may help. Looks like there's only one wire from ECU to coil. That doesn't leave much that can go wrong.
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View attachment 270898

This may help. Looks like there's only one wire from ECU to coil. That doesn't leave much that can go wrong.
where did u get that diagram from
do u have one that shows going to the ECU

also is there a test to see if the ECU is bad i still have dash lights and can get codes
thx farmer
where did u get that diagram from
do u have one that shows going to the ECU

also is there a test to see if the ECU is bad i still have dash lights and can get codes
thx farmer
Shows what going to ECU?

I have a few more I'll try and pull out to post. As far as a test for the ECU it's hard to test for. People chase issues forever and throw all kinds of parts at it before they determine that there's not other possibilities and it has to be the ECU. I didn't see an answer and I'm assuming you did but I have to ask.....did you check all the fuses and relays?
Only other one I have that mentions the coil.
Thx Clark
Well I found the bug
Your help was greatly appreciated
It ended up being a broken wire inside
The plug to the coil
Never would have been able to see with
The naked eye
I was tone-ing the wire and wasnt getting
Any tone on the Y/b wire
So I started at the plug an went 2inch back
And the was no tone, so I started 3inch back
From the plug and got a tone
So I repeated from the start and no tone
So I pulled apart the plug and there it was
About a 1/4 inch after the metal pin part of the plug
The wire was separated from the pin
The plug looks brand new I would have never suspected
It
But it's running
Thx for the help
Farmer
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Careful with the tone feature on multimeters. Glad you found the problem but it can give false readings when you are only looking for ohms. Continuity is only 0-5 ohms and I've found that the tone will go off at more than 5 ohms. Which is bad when all you need is 0-5. Any more than that and its considered not to be continuity.
Was the wire melted at all?

Has the nutter bypass been done on this vehicle?

Sometimes people are doing the nutter bypass and not checking the voltage to the coil afterwards and the voltage is too high and ends up burning up the coil.

A simple ballast resistor will fix the issue

Chief
Thx Clark
Well I found the bug
Your help was greatly appreciated
It ended up being a broken wire inside
The plug to the coil
Never would have been able to see with
The naked eye
I was tone-ing the wire and wasnt getting
Any tone on the Y/b wire
So I started at the plug an went 2inch back
And the was no tone, so I started 3inch back
From the plug and got a tone
So I repeated from the start and no tone
So I pulled apart the plug and there it was
About a 1/4 inch after the metal pin part of the plug
The wire was separated from the pin
The plug looks brand new I would have never suspected
It
But it's running
Thx for the help
Farmer
That's what the forum is all about! Glad your back on the road.
Careful with the tone feature on multimeters. Glad you found the problem but it can give false readings when you are only looking for ohms. Continuity is only 0-5 ohms and I've found that the tone will go off at more than 5 ohms. Which is bad when all you need is 0-5. Any more than that and its considered not to be continuity.
No its KINDA like a grounding feature in my volt tester
it just sounds (tones) when there is a connection between the two pin tester's on the volt meter ( for example) if you had a 5 foot section of wire and you held it on both ends it would sound tone if there was no breaks in the line
if there was a break no tone


SAHARA''
no nothing was melted or anything it was solid
i would have never visually seen it there was no signs of damage
on the backside of the plug. there is a rubber weather plug that the two wires pass through than they connect to two (tamiya pin)type metal connector
where the wire is crimped to, it had broken rite there! and since the wire was tucked into the weather plug, it did not look broken.
the volt meter with a tone feature just made its worth
thx farmer
Ok sounds like I may to look at one I would not have found that
1 - 18 of 18 Posts
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