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1990 4.0 ignition module

V

VAwheeler

NAXJA Forum User
Location
SE Virginia
I have just gotten my motor back in and everything hooked up. I went to try and start it for the first time yesterday and it wouldn't start. I started checking the nornal things and found out that I dont have a spark coming form the ignition module/coil. I have tried to take it to a couple of the local autoparts store to have it tested to make sure that is what the problem is. So far no one has had the correct plug to be able to test it.

My questions are:

Is there anyway that I can test it myself?

What wires on the plugs should be seeing current while starting the engine or while in the run position?

Assuming that this is the problem. The cheapest replacement I have found is $60.99 at an online parts retailer. Is there any where else you guys would recommend looking?
 
Can you send a pic as I am confued about what you are calling a ignition/coil module.
 
33002299-Ignition-Modulelow.jpg


Its located on the right side fender. It is what the wire that comes from the center post on the distributer goes to.
 
By chance does anyone from the weekday crew have anything they could add?


I'll be buying a new module tonight if I can't find anyone to tell me how to test the one I have. I am fairly certain this is the problem but I would like to be 100% sure prior to spending some cash for new parts.
 
I am bumping this thread bacause I am still lost. I just replaced the coil, which is just the top portion of the picture that I posted above. I am still not getting a spark. I now have a new distibutor, rotor, cap, button, and coil. The only thing that I know of that is left to replace is the ignition contol unit. The cheapest I am able to find the control unit is $125.00 and I would like to have some reassurance that there isn't something else that I should be checking prior to spending more money.
 
I have not checked it yet.

According to the FSM to test the CPS you should first unplug the connector for the CPS and test the resistance between connection A and B (as marked on the connector) and the resistance should be 200 +/-75 ohms (hot engine).

Obviously I am not able to get the engine hot if I am not able to get a spark. Do you know what the resistance should be with a cold engine? I will go out and check what resistance I am getting and report back.
 
Well this morning I replaced my CPS, but it wasn't the trouble. The old one was 227 and the new one was 204. Both cold.
 
The larger yellow wire to the module should have battery voltage with the key in the run position.
There really is no way that I know of to test the module without the tester. Or for that matter the trigger signal to the module from the ECU, the trigger signal is an odd wave form that most regular volt/ohm meters can't read well, if at all.
 
xjtrailrider said:
Are you sure your CPS is good?
Click to expand...


Thank you sir...The CPS wasn't bad but it had become disonnected at the plug.:dunce:

Once I plugged it back in I was able to get a spark. I will check to see if I can get it started tomorrow. I really want to try tonight but with is being 1:00 am and the heep currently has an open header, I don't think the neighbors would appreciate me trying to start is right now.:rof:


I will check the resistance of it cold when I go out tomorrow and confirm its resistance against what neonrog posted.
 
8Mud said:
The larger yellow wire to the module should have battery voltage with the key in the run position.
There really is no way that I know of to test the module without the tester. Or for that matter the trigger signal to the module from the ECU, the trigger signal is an odd wave form that most regular volt/ohm meters can't read well, if at all.
Click to expand...


I am getting voltage to that wire with the key in the run position.

According to the FSM the wires should be the following:

CONNECTOR 1:
A: ignition (+)
B: Ground (-)
C: Tach Signal Diagnostic connector D1-Pin 1

Connector 2:
A: Not used
B: ECU square wave input/Ignition coil interface (5v square wave signal)



I think my issue was a bad connection at the CPS. But I would like any and all other suggestions to what the problem could have been just to try and add as much info as possible to this thread for future searches.
 
The larger yellow wire to the module should have battery voltage with the key in the run position.
There really is no way that I know of to test the module without the tester. Or for that matter the trigger signal to the module from the ECU, the trigger signal is an odd wave form that most regular volt/ohm meters can't read well, if at all.

2rpek3l.png


I'd check wire continuity, it costs nothing but time.
 
I don't know if this will help in locating a replacement module but I think it is the same as a FoMoCo unit. You may go back to the parts place with that info and see if they can crossreference it that way.
 
Thanks everyone for thier help. I believe I have located that the CPS was the issue.

I checked the resistance of the CPS this morning and it is reading 220 ohms with the motor cold.

I started checking for fuel leaks this morning just to make sure everything is tight before I fire the engine up and I found that I am still having a leak where the fuel regulator meets the fuel rail. I noticed that I had a leak ther yesterday and put a new oring on it but I guess is not the correct oring. I have a rather large assortment of orings in the shop so I'll go see if I can find something that will fit.

By chance does anyone know if this is the same size oring that fits on the fuel rail side of the injectors.
 
VAwheeler said:
Thanks everyone for thier help. I believe I have located that the CPS was the issue.

I checked the resistance of the CPS this morning and it is reading 220 ohms with the motor cold.

I started checking for fuel leaks this morning just to make sure everything is tight before I fire the engine up and I found that I am still having a leak where the fuel regulator meets the fuel rail. I noticed that I had a leak ther yesterday and put a new oring on it but I guess is not the correct oring. I have a rather large assortment of orings in the shop so I'll go see if I can find something that will fit.

By chance does anyone know if this is the same size oring that fits on the fuel rail side of the injectors.
Click to expand...

Yes its the same "O" ring, I buy mine at the local hardware store but the dealer will rape you if thats your last resort. They sell in packs of 13 at the dealer, 6 for the rail, 6 for the intake, 1 for the fuel pressure regulator.
 
By chance do you know what the part number is for the ones that you are using?
I tried some from Autozone. I got the Help! assortment pack in both the metric and standard sizes. The first oring I tried is the one that is leaking now.
 
VAwheeler said:
By chance do you know what the part number is for the ones that you are using?
I tried some from Autozone. I got the Help! assortment pack in both the metric and standard sizes. The first oring I tried is the one that is leaking now.
Click to expand...

No part number, "O" rings just go by size. If you have an old one take it with you and match it up, keep in consideration that the old "O" ring will be smashed a bit from installation so compensate that when you compare them to the "O" ring charts. Most hardware stores that sell plumbing supplies will have the charts to make comparison to. You may have to pull your rail and take one of those with you if you do not have an old one. replace the ones on the rail/injectors while your at it. A little vaseline coating on the "O" rings will help with installation and keep from any accidental damage to the "O": rings when inserting.
 
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