Ignition problem 1982 4G52

[KGR1989]

Alright, so the other night I was driving on the highway and suddenly it backfired and it lost all power. Still had lights and all though. Coasted to the side of the road and checked what I could. Friend came with a trailer to get me and brought it to his place where we've been working on it some the past few days.

So we've followed it all down to the ignition system. Tested the coil and wasn't getting anything from it so went ahead and replaced it, but still the same result. So pulled off the cap and rotor button and cleaned up them. They're not in perfect shape and I'm going to replace them, but I don't believe that it's the problem because the coil isn't even getting signal to fire.

Now, I've never messed with anything this old, but behind the rotor button there's what looks to be an early style ignition control module that's kind of like a small coil that goes around the shaft of the distributor and screws in at two points and has two wires that come off of it going back to the coil which I assume is for the signal to fire? Is there a way to test this? It kind of looks like a points eliminator?

Thanks in advance and excuse my lack of knowledge on the older stuff lol.

[geezer101]

Any chance you can post a pic of the distributor up for us? The only time I've ever messed with a 4G52, it had a points distributor in it. Judging by what you've said, it sounds like the igniter/pick up in the distributor died. You can swap the distributor from a 4G54 into it.

[KGR1989]

I'll have to take one tomorrow. I don't think the actual distributor is bad, but I'm not sure of how to test it. From what I can understand about it just by looking at how it's wired it looks like the pickup/igniter sends a signal of some kind to the coil. The two wires that come off of it one goes to the negative side of the coil and the other goes to the positive.

Is the distributor in the 4G54 a newer design? I've never seen a points style distributor, but I don't think this is one. My dad said that it seems like the part I'm describing is a points eliminator of some sort, but a factory style of it. To me it kind of looks like an early style of an ICM (ignition control module). I'll post a picture tomorrow though and guess I'll go from there.

[KGR1989]

I just realized that it blew up the picture and didn't fit it to the forum sizing...my bad lol
There's a smaller one lol

[KGR1989]

Found it on rockauto, but it's also showing a separate ignition control module that it says is located inside the distributor, but I don't remember seeing one? Is it possible that some engine variants had one and some didn't? Sorry for all the questions

[KGR1989]

So, I found the actual part. It's a distributor ignition pickup. Here's a picture of it. It sits behind where the rotor button mounts to and to take it off you just take off the bolt in the center for the shaft that the button mounts to.

[StarquestMan]

I agree with geezer, it sounds like the igniter is bad. they go by different names like igniter/icm/coil pickup etc. its job is basically like you mentioned it being a replacement for points in an older distributor. its a self contained module that contains a pickup coil and some circuitry to switch on and off ground to the coil to generate spark. one wire powers the circuitry inside and the other is coil ground if i remember correctly. there may be a way to test it but ill have to check my service manual for my 87' that uses a very similar module. i had one die on me and it acted like a dead coil. if you replace it you may need to set the gap between it and the rotor for it to work properly.

[StarquestMan]

i studied your picture better and realized how your pickup coil is separate from the icm on your distributor. you should be able to check the coil with an ohm meter and if it checks out than the icm is probably bad. i bet that the plug in icm part of it is bad but the coil could have gone too so i would check it out too

[geezer101]

Even if the it's only the coil, there should be some life in it. It will misfire and die at higher rpm, or alternatively it will quit when it gets hot (classic symptom of a cracked ballast resistor) If the coil is original, it will be really tired - a coil normally lasts about 10 years before it starts to break down.

[KGR1989]

Ah, ok that all makes sense. I went ahead and ordered a few things from rockauto since it was pretty cheap and can't hurt to replace it all. Basically the only thing I will have that isn't new in my ignition system will be the actual distributor itself and I spent around $55 shipped to me for it all.

When it gave out it backfired pretty loud one time and then just lost all power. The actual ignition coil was replaced at some point with an off brand "performance" style one. It looks to be pretty old also. The pickup coil that I was mentioning earlier was the original part, so it's nearing 40 years old.

If this doesn't fix it then the only other thing it could be is the actual distributor, I think...I'll have new plugs, wires, pickup coil, cap, rotor, and ignition coil. Beyond that I don't think there is anything else other than the distributor, correct me if I'm wrong though.

[geezer101]

Once you have replaced anything electrical related to the ignition system, you're only left with the distributor itself. The counter weights for the advance can have the springs break or come off which causes erratic ignition advance or the vac advance servo can split which will leave the engine response down on initial open throttle. The advance mechanism can also gum up with junk which will prevent the ignition curve from ramping on throttle.

[KGR1989]

Alright, so the parts came in last night and I just went to install them and I'm still getting no spark. I'm not entirely sure I've got everything hooked up to the coil properly though. The old coil is labeled (+) and (dist) which I assume the distributor is acting as a ground for the coil? The new coil is labeled (+) and (-) and I have the main power and the ignition wired to the (+) side and the two signal wires from the pickup coil and the tach to the (-) side.

Of the two wires off of the pickup coil, one of them has a rubber nut cap to slide over the top of the ignition coil stud that it goes on. So that one can't be hooked up to the (+) side because the main power has one of those as well and they can't both go on the same side. I've switched the second wire coming off of the pickup coil to the (+) side, but still no spark.

Now, the new pickup coil I bought from RockAuto did not have a new ICM I guess you would call it. It's just the actual wires with the coil itself that goes around the distributor shaft and out the side. Having a hard time finding the ICM online and parts stores aren't being much help either.

I'm just hoping that someone will tell me I've got it hooked up wrong and that will solve the issue, otherwise I'll have to search to find the ICM and hope that it's the problem.

Here's a picture of how I have it wired up. Hopefully it's shown a bit larger in the actual reply than it's currently showing on my screen.

IMG_1741.jpg

[StarquestMan]

I think you may have two problems. i see right off the bat that both wires coming from the distributor are tied to coil ground (labeled "dist" on your old coil) the black wire with the white stripe coming from the distributor should be paired with the black wire with white stripe from the harness side. the black wire with white stripe on the harness side is your 12v supply to the coil and the ICM needs power to function too so it has a matching color wire that sends power to it. the blue wire is correct in that it provides a ground path through the ICM and im not sure what the light and dark brown wires go to (im guessing the dark brown is going to a tach and/or computer ignition signal and light brown being B+ for said computer?). the second thing is probably a bad ICM itself but the wiring should be corrected first. if moving the ICM black w/white stripe over to the coil + doesn't bring back spark keep the two black wires on the + terminal and replace the ICM

here is the icm link
https://www.rockauto.com/en/catalog/...ule+(icm),7172

[KGR1989]

No luck, so I'll order a new ICM. Pretty sure that's all it could be now other than the actual distributor, but I don't think that's the problem. Unless there's something else I'm missing that I haven't replaced that is.

[KGR1989]

Ah, awesome! I'm gonna go try it out right now and I'll post back with the results. Hoping it will fire up lol. Thanks for the ICM link too! Not sure why I couldn't find it?

[KGR1989]

Ok, so the ICM came in today. I installed it and still no spark off of the coil. I paired the wires as Starquest mentioned and also tested to make sure I'm getting power to the coil and I am getting right at 12V to the coil. Swapped the new coil out for the old one just to see if maybe the new one is bad and still the same result.

So, new cap, rotor, pickup coil, and ICM and it's still not getting spark from the coil? What am I missing? I might be wrong, but if the ignition switch were bad then the engine wouldn't turn over right? It can't be a bad distributor could it? If it were bad it'd still get spark off the coil, right? Also, to test the coil spark I have done it a few different ways. First with the wire off the coil attached to a spark plug. Then with the wire with no plug, and then another time with my wife turning it over and I was looking inside of where the wire plugs in but with no wire.

I'm stuck lol

[Giovanni89]

A multi meter will be your friend here. Start simple. Turn the ignition to the on position. You should have about 7-9 volts at the +side of the coil. There are usually two wires from the ignition switch. One provides 12 volts to the ballast resistor when the key is in the on position, which feeds 7-9 volts or so to the coil. The other provides 12 volts directly to the coil when the key is in the start position (this is often connected to the second side of the ballast resistor and not directly to the coil). This is because the starter drops your battery voltage, and the ballast resistor would drop the voltage too low to get a good spark.
I'm not familiar with the 4g52, but I'm not sure why there are three wires to the negative side of the coil. I would think there would only be one (two if you have a tachometer hooked up). The coil grounding wire from the icm. If the coil is constantly grounded it won't throw a spark. The way they work, They are grounded, and build up a magnetic flux in the primary winding. When the "points" or icm open, the current stops passing through the primary coil. The built up flux has nowhere to go, so the flux field collapses into the secondary windings, and on the the spark plug. The ratio of secondary to primary windings gives you the massive voltage step up, like a transformer.

[travhous]

Black/White from distributor +
Blue from distributor -
Black/white harness (ign.) +
Small brown (tach) -
Large brown (starter?) +

When the ignition key is turned to the start position it cuts power to the entire truck. The coil then gets its power from the starter while it is cranking. I'm guessing that the larger brown wire is from the starter.

There should be a ballast resistor also that is missing, although that is not your current issue. There's a good chance that not having the resistor burned up the igniter in the distributor originally.

[geezer101]

+1 on the ballast resistor. Not having one in place will drastically shorten the life of the ignition components. If you're getting power into the coil, then the problem is between the coil and distributor. No power to the coil, there's something up from the ignition switch.

[KGR1989]

Alright, I'll try flipping the browns around like you mentioned and see if that works. Not sure where the resistor is supposed to be. I bought the truck like this and the previous owner didn't do much to it in all the years he owned it. I asked him about the ignition situation and he said he hasn't done anything with the coil or ignition in the time he owned it which was 10+ years.

I do know that there's 12V to the (+) side of the coil when the key is in the on position and when it's being cranked it doesn't change. Tested with my friend the multimeter lol. I do have a tach hooked up and I *think* it's the small brown wire with the newer red end on it that's in that picture I posted.

Currently I have it as follows.
Black/white from dist. to (+)
Blue from dist to (-)
Black/white from harness (+)
Small brown from harness (+)
Small brown with red end (-) and I *think* this is for the tach

I'll have to reconfirm that it's for the tach tomorrow. It's currently 1AM and raining.

Really appreciate the help on this though. Been about 2 1/2 weeks since I've had it running and I'm missing my little beater truck lol. Wife isn't too happy either with all the broken down cars we have. Currently we own 5 vehicles and 2 are running LOL. My Trans Am's oil pump took a dump on me back in September and I have yet to drop the oil pan and repair it and I've got an older Honda Accord that has bad alternator (in a horrible spot) and my wife lost the keys to it SO I've been driving my Miata around until the truck is back up. I really hope my car luck gets better in the new year/decade

[travhous]

At some point there should have been 2 positive wires, one on each side of the ballast. One would have been hot when the starter was spinning and the other while the key was on. Whoever removed the ballast may tied some wiring together elsewhere. I would double check the black/White from the harness and make sure you getting power with the starter is cranking. If not check the brown with red crimp.

Do you have a factory tach or aftermarket?

If it is a factory tach I would assume the smaller wire from the harness goes to the tach.

The brown wire with the red crimp has me stumped. Where does it run to?

[travhous]

IMG_20191217_163955.jpg

[KGR1989]

Well then, it's obvious mine is missing something LOL, but it was working without it before so I doubt that's the reason it isn't currently running. I'll definitely get that though and after I get it running I'll wire it all up properly.

It's been raining all day long so I haven't gone to verify which wire goes where, but I'm pretty sure I remember the small brown wire with the red connector going to the tach through the firewall. The other brown wire goes into the harness.

So looking at your picture it looks like power goes to both sides of that ballast, right? One source from the ignition and the other from the starter I assume as mentioned before? Then there's a jumper wire to the coil? Basically mine seems to be configured the same, just without the power input from the starter and no ballast setup. Tomorrow's weather will be better so after I get home from work I'll verify which wires do what, I'll check all the wires for power separately to verify which ones are giving power, and I'll see if I can come up with any other configurations that would make sense to try.

My dad keeps saying I need to find out if there's a separate ignition switch and see if it's bad. I guess the way to test the ignition switch would be to have my wife turn it over while I use a multimeter on the signal wire, correct? Also, wouldn't the engine not turn over if the switch was bad and would it have shut off randomly while driving? I would assume that the signal from it is only to start and not to continuously run.

[StarquestMan]

Hang on! sorry for the delay, ive been super busy with school. it appears that they didn't start using a ballast resistor until 83 or 84, i looked for a wiring diagram but could not find one. I looked up a coil on Napas website and it shows one with "No External Resistor Required" printed on it. I can find ballast resistors for 84-86 trucks and 87-89 trucks with a quick google search but all the rest are just generic universal type. Unfortunately I don't have a parts catalog that covers 82 to confirm it 100% but im pretty sure yours doesn't need the ballast resistor, assuming you ordered a coil specified for an 82. do either coils have any markings on them mentioning ballast resistors? like others said the heavy brown wire that was added could be a work around for a flaky ignition+ contact in the ignition switch when turned to the start position. if all that fails check the connections between the ICM and the pickup coil/wire assembly. also make sure the gap between the rotor and pickup coil are close enough to trigger the ICM properly.

[KGR1989]

Alright, so I did some messing around and testing today after work and here's what I've got.

That brown wire with the red end goes to the tach. The other brown wire is the signal from the ignition switch. When I turn the key I am reading ~0.20V from the ignition switch. That seems a little low doesn't it? The black with white stripe wire from the harness is power and it's reading 11.3V. When it's all hooked up to the coil it's reading 11.3V on the (+) side of the coil and it's also reading roughly the same on the (-). I thought this was odd. Shouldn't the (-) side read nothing since it acts as a ground for the ignition system? I switched back to the old ignition coil and it's the same result on it as well. Correct me if I'm wrong please lol I'm no expert.

So far I've got a new distributor cap, rotor button, pickup coil, ICM, wires, spark plugs, and coil and I'm not even remotely seeing a spark from the system at all.