thook

There's hundred of threads on this relay gig, but I can't find a one on how to test it or remove it. The CEL is not coming on upon ignition, so obviously the ECU is not getting power. The 15amp fuse is fine, so I'm guessing the relay....I don't know.???? I can't get the FSM to load up and I'm right in the middle of trying to get the thing running. Won't start, but definitely getting fuel.

Brief history...
A while back I was trying to diagnose the thing continually dying. Would run for a bit and then just die. So, I was testing some things at the ECU terminal because the parts in question (at the time) were fine....still are. So, I thought maybe signal to the ECU. All that tested fine, too. All can figure at this moment is maybe I blew the relay testing everything, but I can't imagine why.....I was following the FSM guidelines to a T. Which raises a question. If the EFI relay was going poop, would it do so intermittently causing intermittent stalling out? All I know is when I jumped the FP and B+ terminals to test the FP relay and VAM (again, at the time), it would run. Then I dropped the whole business to take care of other things, and now getting back to it....no CEL, no start...AT ALL.

Sorry for the ramble.

'92 4rnr 3.0....uhg.

thook

How 'bout that....now the FSM will load, so now I know how to test it. But, it doesn't say how to remove it. Just pull it out? I've tried and the bugger is in there real good. So, I thought maybe there is something else to this? I don't want to break anything, eh.

thook

Bump.....

1989toy4wd

just pull it out with an even upward motion, there is really no trick to it, over the years they just get stuck, put some dielectric grease on the terminals for next time

thook

Thanks anyway. I got it out....with some long needle nose pliers. Haven't tested it yet, but I got it out.

thook

Tested the relay and it failed test one in the service manual....no continuity on 1 and 2 terminals. However, it passed the relay operation test. Still, when I reinstalled it in the vehicle and turned the key to ignition it did not energize or "click". So, I tested for power to the fuse and to the relay terminals in the box. Voltage!!! I'm a little confused because it seems as if it should click if I'm getting voltage. ????? Anyone have a clue?

I'm picking up a new relay at O'Reilly to test against the original. I'm hoping the relay is all it is. Otherwise, it means the stinkin' ignition.....I believe. I'll post later.

thook

Right.....so, the new relay is in. It was definitely bad 'cause the new one clicks while the old one didn't, but the truck still won't fire. Plus, the CEL still won't come on when I turn the key on to ignition. If it were just the bulb, it would still fire, but it doesn't. I'm getting power to the 15amp fuse still, as well as the relay posts. BTW, which posts should be getting power...12v's?

So, the FSM says check the ignition circuit. Since I've never had to diagnose the IC, would someone mind pointing me in a direction. What are the common things to look at and what have you all found to be the culprit in your experience.....if you've had a similar one? I'd like to try and track this down today if at all possible so's the wife can use her vehicle. It's gettin' on 4wd season.

Thanks

thook

Wow...I'm the only one responding...and it's my own thread. Come guys! Don't tell me I'm going to have to go to another forum for help!

So far I've tested the coil and it read "open" (or zero) on the terminals where it should read.36-.55 ohm on "primary" and 9.0-15.4 ohm on "secondary"....both cold. What is this primary/secondary thing all about?

thook

bump-p-p-p-p

rdharper

So back up a bit. Does the truck show the original symptoms... cranks, starts, then dies?

Not terribly clear on your symptoms here.

thook

Thanks for responding.

Okay, well...it cranks, but will not fire. Just turns over and over with no combustion. It's definitely getting fuel, just not ignition.

thook

I've tested the pickup coil at the distributor for ohms and it checks fine. I'm getting voltage to the ignition coil, but the ohm readings are out of spec. Both primary and secondary read 11.75k ohms while cold. The primary is supposed to check at .38-.55 ohms, and the secondary at 9-15.4 ohms....cold. I checked with a friend/mechanic who didn't seem to think that was really a reason to call it bad just yet. I'm sure he has his reason, but I was unable to finish the conversation with him about this. So, I'm still unsure of it.

rdharper

I bumped the thread from whence the following comment came:

check the bulb first, if its good then you ECM is not getting power, check the EFI relay and EFI fuse, make sure you hooked everything back up correctly, especially grounds

This sounded a bit like your problem, as he couldn't start his either, and no CEL light.

On the ohm reading... there is a big difference between the reading you get.. kohms mean a thousand ohms.. something not right there. Your FSM should tell you what it should be. If the readings you quote are correct... it ain't right.

thook

Some other things...(sorry for breaking it up, my computer was acting up...had to reboot)

Almost a year ago, the fuel pump began to continue running long after the key was turned to ignition. It didn't do it all the time and still doesn't, but it does do it some. I told the mechanic of this and he didn't have a happy expression. Since the CEL won't come on when I turn the key, he's concerned about the ECM itself. But, being conservative as he his he's reluctant to immediately blame it. To him, it's the last on the list. In the long run, the ECM may be the problem (or part of it), but he said it could be the igniter....depending on the style of the system and how everything in the system relates to one another. So, I found a test to run (the FSM is very inadequate in this dept.) on this forum....
https://www.yotatech.com/forums/f2/n...89-95-a-10543/

I've attempted to run this test over, but I'm unclear on all of this instructions. Can you read this and tell me whether or not it is clear to you? Then, I can ask you what I need to know about it.

Thanks

thook

Yes, it could be the bulb, but that wouldn't cause it not to start. So, I'm not as concerned about the bulb as I am why it won't start.

The relay was bad, so I've replaced that. The fuses all are good...tested them.

When I say "K ohms", I'm using a 20m scale (reading 11.75) assuming that is the correct scale to use. So, I'm interpreting that in k ohms. Maybe I'm wrong about that, but according to the FSM they should definitely not read the same....at all! Interestingly, to check myself and the readings, I set the DMM to 2000 scale and the meter read infinite. ????? I have no idea what to make of that, except that maybe the 20m scale is the one to use.?????

thook

Uno momento...reread your post.

I check the fuses under the hood and behind the kickpanel....all of them. I know of the 15amp EFI fuse next to the relay, but are there any others related to the ignition system that I may have missed?

Incidentally, I've not taken anything apart in the way of wiring/grounding, so that would be moot. Except, I suppose something could have come loose or corroded. I will check that. So, I will return shortly. Thanks, again.

rdharper

I agree with the comment that the ECM is the least likely problem.

On the "tip" you referenced, that is specifically for no spark. Are you getting no spark?

On the ohm readings.. 20m would mean megohms.. millions of ohms. That is essentially an open reading. You can hold the leads between your fingers and press... and get a reading on that scale.

Make sure your meter reads zero ohms when the leads are shorted together, or close to zero on the lowest scale.

What is the correct value.. the values you quoted as correct "0.38-0.55 ohms, and the secondary at 9-15.4 ohms....", are very low values. .38-.55 ohms is essentially a dead short. 9-15.4 ohms is also low. If that is what you should read, you should be able to use the lowest scale. Make sure your meter is reading correctly... and you are making proper contact. Knowing how to use and read that meter is a valuable skill.

thook

Yeah, I'm still learning about using that contraption. So, my knowledge and skills are a disadvantage, but I learn more as I use it. I do know this...the meter is working correctly..it's practically new. The leads, when contacted on ohm function, read 0. I can test a good fuse and still get open.

Well, I think it's safe to say I found the problem.....atleast a big part of it. Should've just looked there first. 1/4 of the ECM is completely rusted, corroded, and fried on the board. I was reluctant to take it apart for fear of damage, but curiosity won me out.....since you brought up "no power to the ECM". Glad it did....sort of. Atleast I've gotten somewhere with it.

Still, I would like to check the other ignition components to see if anything else got fried considering the relay was also bad. So, using the info you've given me about the meter I will retest the IG coil, but I'm still clueless on the igniter....about how to test it. I posted that link. Do you understand what he is saying? I'm under the impression, though, this test is performed with a functioning ECM....which might make it difficult to run it.???

About the ECM...
This had to have happened when I wrecked the vehicle last Jan. The windshield was busted out on a day it was raining. As well, it sat in the tow yard uncovered for a substantial amount of time until it was finally covered up. FUDGE!!!!!

thook

Oh....btw, I'm getting power TO the ECU.....atleast...hahaha. Pffttth!

as2sb3100

So where was your EFI main relay? I couldn't find mine. I ended up just running power from the battery to the ECM and fuel pump.

oh, my problem was that I was blowing the efi 15amp fuse at random.