No start no spark

[sprokit]

HI all. First off, let me say I've read all that could find aon here about starting problems. Anyhow, helping a buddy with his 91 Ex EB. The problem start a few days ago. It just died on him. He got a jump and made it home, but after a couple hours, it would not start.

When I got involved, I tried to jump but nothing but clicking from the starter relay, I changed that, now it cranks. The fuel pump sounds fine. I check all cylinders for spark, but there is none. I suspected the coil pack so I got out my meter and checked resistance across the three coils, I show btwn 12.3k and 12.4k ohms on each. Is this within specs? I checked the connector and it looked ok. I also (after seeing it on here) changed the CPS.

I also checked the fuse block continuity (also saw that here somewhere) That checked ok, voltage where its supposed to be and high resistance but not open on the other half.

Question, how do I check to make sure the input voltage to the coil pack is ok?

Also, is there a way to check the Ignition mod behind the battery on the rad support?

Is there something I missed that would prevent the coil pack from sparking? We just put all new plugs and wires on too.

I know that I could just go out and buy a new coil pack but up here in AK its $240.00. I'd rather have an idea that its bad before I tell my buddy to lay out that much. Same thing for the ignition module.

Any help you guys can provide would be greatly appreciated.

O BTW, the CEL comes on just before I crank, and goes out when the key is turned all the way to start. We also did not get any codes either.

 

[Bashman]

Welcome to the site.
For the ignition coil, the secondary resistance should be 6.5-11.5 K-ohms and the primary resistance should be 0.3-1.0 ohms.
For the ignition mod:
(ref numbers are from1-12 with 1 being the top terminal)
Check power to the ICM. With a voltmeter probe terminal 8 (red + wire) and check for battery voltage. With ignition "ON" but engine not running you should have battery voltage. If no voltage then possibly the PCM or wiring. Turn ignition "OFF" and using an ohm meter check continuity between terminal 9 and and battery ground. You should have continuity, if not you have an open ground. Check resistance between terminals 5 and 6. You should read 2k-3k ohms. If not check the CPS (I know you changed it already). Check the circuit from the ignition module to the SPOUT (spark output) connector on terminal 3 (pink +) for a complete circuit. Continuity should exist. If these results are good, replace the ignition module.

 

[sprokit]

Questions

Thanks for the help. A few questions though. Can you tell me how to check the primary and secondary resistance on the coil. All I did was measure across each two top terminals. That measure around 12.3k I am assuming you are measuring from one of the connectors on the side to a plug terminal. There are however, four pins in th side terminal, what is the 4th for?

next, for the ignition module, since the battery blocks it, I assume you mean checking the terminal on the harness connector while its disconnected (but I could be mistaken)

Lastly what is the PCM?

Thanks,

I should be checking this Wed evening

 

[Bashman]

For the secondary resistance, check terminals across from each other, in other words "paired companion cylinders":1&5, 2&6, 3&4. For the primary, the connections on the side of the coil pack are layed out like this: the first three terminals starting at the one closest to #1 cylinder's connection are negative, the fourth and furthest from #1 is positive. Connect to the positive, then each of the negatives, the resistance should be about the same.

For the module, yes you are correct. I should have mentioned it is done on the disconnected harness. #1 should have an offset tang by it and #12 should have a centered one.

The PCM is the powertrain control module a.k.a. the computer. On Gen 1 X's (91-94) it is located behind the passenger side kick panel.

Let us know how you make out.

 

[sprokit]

Here's where I'm at

Ok. I have finished checking as you suggested. here is what I have. BTW, still no spark.
The coil primary resistance is .6 ohms all 3 of them. The secondary is still 12.4k ohms, you and Haynes say this should be between 6.5 and 11.5k ohms.
I also checked the ICM plug as you said. I have battery voltage on pin 8, ground on pin 9, continuity with the coil pack on 10, 11, and 12. (got that from haynes)
5 and 6 (CPS wires, I have 650 ohms, not 2-3k like you said. This is the same as the CPS it self. I wnet and got another CPS from Napa (took my meter and the resistance was almost the same) I am going back tommorrow and check the others they have.
I am a little confused about checking the # 3 pinwhich is the SP OUT. Where am I checking the continuity? Is it from the pin on the connector to the SPOUT connector?

ANyhow, my next step is gonna be checking the coil triggers with a LED light.

My two concerns here are the CPS resistance and the coil pack resistance. By checking the coil trigger, I think I can verify whether the problem is in the ICM or PC or if I need to go ahead and replace the coil pack.

Thoughts?

 

[Bashman]

I believe the check is as you said, one lead on the #3 terminal on the ICM and #3 on the connector. I wouldn't think that your secondary reading a little high would be a problem. I can check the connections out on my truck tomorrow and let you know what my readings are if you like. Right now it's cold and snowing.

 

[sprokit]

Got it started Thanks for the help

Alrighty now.
Anyhow, It turned out to be a bad OCM, here's how I found out.
On my way to my buddies house, I stopped at a local junk yard and checked the resistances on a couple coil packs, they all read what ours did, the I went by NAPA and checked anew one, their budget model was the same but the Echelon version was within the Haynes specs. The guy there so it shouldn't make a difference,

I also checked out the resistance across a couple more CPS' and they were all round 600ohms, versus the 2k-3k that haynes said (hey they've been wrong before). Anyhow, I picked up a low voltage test lamp and headed for the EX.
I checked the coil trigger by hooking the test light to the battery + and each neg lead on the coil connector, had my friend crank it, the light shoul've flashed.but it didn't I also checked the voltage to the CPS, HAynes says with the key in the "On" position voltage on one of the CPS connector leads to ground shoud've been 1.5 volts, well they were both battery voltage. Haynes also say to check the CPS, with it in place, take a volt meter set for AC and measure across the CPS terminals and crank the engine, you should see a pulsing AC voltage( they didn't specify how much) I saw .6 to 1.2 volts.

Anyway, when I was at NAPA earlier they said they have an Ignition Mod tester, so we took the ICM to Napa and put it on the tester, it was bad,,,,yea til we found out that the new one was regular $249...even with my military discount it was still $220 and my buddie couldn't afford it, so we went to a junk yard and pulled one off a 92 Ex, same part number except the year, paid $10 as is, back to Napa, and it tested fine. Ohh BTW, when I tested the CPS on the vehicle, I tested the old one and it was good, so we got a refund from NAPA with no hassle.

The guy at Napa said they just got this tester last year. It seems pretty thorough as it took about 4 minutes per test they recommend testing three times


Anyhow, the Junkyard ICM did the trick and it started right up.

Oh, just to verify what Haynes said, I rechecked the CPS connetor and saw 1.6 volts acorss one terminal to ground only, not both.

Thanks for your help.

 

[Bashman]

Glad to hear you figured it out and it's running fine.