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3VZE not sparking & Check Engine light won't come on.

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Old 08-28-2009, 11:35 PM
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3VZE not sparking & Check Engine light won't come on.

Alright first off I've done a ton of searching so far with no luck at all.

The Problem: My 3vze will no start. It turns over fine but is not sparking. I've check the ignitor coil to spec and its good. I've checked the distributor's pick-ups and their good. From what I've found there's no way to check the Ignitor to see if it's good so I tried one from a junkyard and still no luck. I've also tried to pull the codes via the check engine light and the check engine light will simply not turn on or flash whatsoever. It won't come on when put the key in or when I jump the diagnostic plug. I've replaced the bulb and run troubleshooted with no luck. This is starting to make me thing the ECU is bad. I've been starting to look into the fuel injectors but if the thing won't spark there's really no point in proceeding any further.

For a little background, this happened once two days before it wouldn't start at all. When it first happened, somehow through pulling the battery ground and pulling the high tension cord (aka the sparking wire from the ignitor coil to the distributor) it started right up. When this happened, it didn't die while driving, just turned it off one the night and now it won't start at all.

As of right now I have 2 ignitor coils that are good according to the FSM and 2 ignitors that I have no way to test to see if they are good. Is there any way to see if the ECU is ok? Any ideas of what to check/replace next?

Thanks in advance for any help.
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Old 08-29-2009, 08:30 AM
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These are the symptoms when the EFI relay isn't working. I actually have my kill switch installed in the wire that comes from the IGN fuse to the EFI relay to disable the ECU. If the ECU isn't getting power then the ignitor won't be getting power and will appear to be bad. So check for power to the ECU first.

The check engine light won't come on if the ECU isn't getting power from the EFI relay.

Check the IGN fuse in the driver's kick panel fuse box (supplies power to the coil side of the relay). Check the EFI fuse in the engine compartment fuse box (supplies power through the EFI relay to the ECU.) Check the "gauge" fuse in the kick panel (supplies power to the check engine light). I have had a loose fuse socket cause intermittent problems like yours also so try moving the fuses with the key "on" and see if the check engine light comes on or flickers.

If the fuses are good, then the EFI relay may be bad. Pull out the relay and test it for operation.

If the relay is good, check for 12v on the hot terminal of the relay socket with the key off. This is coming from the EFI fuse which is hot all the time.

If the power is good, check for 12v on the coil side of the EFI relay with the key in the "on" (not acc) position. This is coming from the IGN fuse, which is hot with the key "on".

If all this is good so far, you need to test the ECU itself. Pull off the passenger side kick panel and you'll see the ECU. There are three 10mm bolts that hold it in place and it helps if you unbolt it and pull it out to access the terminals.

As you look at the ECU from the connector side, the two white with red stripe wires on the lower right are the power wires from the EFI relay. Check for 12v on both with the key "on". If you have a manual trans then the seventh wire from the bottom right should be violet and comes from the check engine light. Pull out the connector to prevent any accidentally touching the wrong wire and ground that terminal with the key on and the check engine light should come on. The "gauge" fuse supplies power to the check engine light so check that if the light doesn't come on.

If all this checks out, then it's time to try testing and replacing parts.

Good luck,
Bugs

Last edited by bugs1961; 08-29-2009 at 08:35 AM.
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Old 08-29-2009, 08:54 AM
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I see bugs1961 responded while I was typing this post. bugs1961 has given good advice and is obviously experienced. Since there is some more detail below, I'll post it but some is going to be redundant with bugs1961's stuff. Anyway, here goes:


If you're not getting a CEL it could be a burned bulb, no power to the ecu, a bad ecu (prolly not) or a bad connection/ground.

First check B+ in the check connector with ignition on. If you don't have power, it could be a bad efi relay, ignition fuse in drivers kick panel fuse box, bad ignition switch, or a bad efi fuse in engine compartment fuse/relay block. I'd check for power on both sides of the ignition fuse first. If no power and the fuse is okay, check the efi fuse and check for power on the battery side of the socket. If all that checks okay, prolly the ignition switch or a connection to it. If both sides of the ignition fuse do have power, prolly the efi relay.

If B+ does have power, check for power at FP while a helper is cranking the motor. If it has power, the ecu is receiving power and is working at least well enough to power the fuel pump, making a bad ecu less likely.

If you want to troubleshoot spark, next step would be to check that the coil and igniter are receiving power from IG2 on the ignition switch. Check for juice on the positive terminal of the coil when ignition is on. If no power (and B+ and FP are powered), then probably a bad connection between ST2 on the ign switch and the coil and igniter. If the pos term of the coil has power, then either you got two bad igniters or the igniter is not receiving IGT from the ecu. Verify IGT has continuity from the ecu all the way to the igniter. To check wires in connectors, use a back probe fitting on your multimeter or push sewing needles into the connector and press the multimeter against them.

If IGT has continuity between the ecu and igniter, then prolly a bad ecu or bad connection between the signal coils on the distrib and the ecu, or a bad E1 ground. If you have a good automotive multimeter that can record max volts or has a peak hold feature, you can check for hot pulses between the IGT and E1 terminals on the ecu when cranking the motor. Place the neg term of the multimeter on E1. If you are seeing pulses, try the neg test lead on a chassis ground. If no voltage, then the E1 ground is bad. It's shown as grounding to the drivers side post, but I haven't had to track mine and don't know exactly where it is. You may have to follow the wire.

If there is no voltage while cranking between IGT and E1, then either try a different ecu or take the time to verify G1, G2, NE and G- between the ecu terminals and the distributor terminals.

Good luck. Please post back with your findings.

Last edited by sb5walker; 08-29-2009 at 09:14 AM.
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Old 08-30-2009, 11:25 AM
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I just got finished checking the fuses, efi relay and power to the ecu. All of which are working properly according to bugs' post. I also grounded the violet wire which finally made the check engine light turn on. Now what exactly does this mean? Is the ecu fried?

I'm going to check sb5walker's suggestion next but I'm really curious to know if all of the problems are relating back to the ecu. Let me know what you guys think.
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Old 08-30-2009, 02:58 PM
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It was fuses for me - I didn't see bugs reference to the inside fuse at first. I blew that one trying to jumper the fuel pump - Doh!

Last edited by pcpackrat; 08-30-2009 at 03:00 PM.
Old 08-30-2009, 04:56 PM
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I had the same problem a while back and it turned out that one or two of the pins/wires on the VAFM was not make a good contact. What I did to correct the problem was unplug the female pin/wire (connector) harness from the meter then took a smoth wire brush and cleaned the pins then made sure that all wires have good connections. After the check - plugged the connector back. So far the problem has not come back.

hth--my 2cents.
Old 08-30-2009, 08:14 PM
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unplug the AFM and see if the CEL comes on in the ON position. I had something similar with mine, and the AFM was bad. Replace the AFM if that is the issue.
Old 08-31-2009, 05:36 AM
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Originally Posted by Tdubbs05
I just got finished checking the fuses, efi relay and power to the ecu. All of which are working properly according to bugs' post. I also grounded the violet wire which finally made the check engine light turn on. Now what exactly does this mean? Is the ecu fried?

I'm going to check sb5walker's suggestion next but I'm really curious to know if all of the problems are relating back to the ecu. Let me know what you guys think.
Hi Tim,

Sorry it took a while to get this PM but I've been away from the computer. The FSM has you test for proper ground at the ECU next. In the ECU diagram picture the red arrow points to the E1 terminal, which is one of the grounds. The wire is the 4th in from the left on the lower row and is brown without a stripe. The blue arrow points to the violet wire you tested to see if the "W" circuit (check engine light) works.

Check for ground continuity at the E1 terminal (connector plugged in, key off) with a known good body ground near the ECU.

No continuity: bad ground wiring or connection

Good continuity: bad ECU

It's a bummer but unless the ground has a problem, it's looking like an ECU has failed.

The MFI or FI section of the FSM has a complete troubleshooting section for the ECU. If you go through that you'll find out if the ECU has problems beyond the check engine light.

Take care,
Bugs
Attached Thumbnails 3VZE not sparking & Check Engine light won't come on.-ecu-terminals.jpg   3VZE not sparking & Check Engine light won't come on.-ecu-w-circuit-test.jpg  

Last edited by bugs1961; 08-31-2009 at 06:03 AM.
Old 09-02-2009, 10:09 PM
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Well I started to go through what Bugs said and then decided to plug my ecu back in just to see what would happen. Sure enough the check engine light came on and it started right up. Looks like it was a bad connection or something. The ecu was out overnight which might have reset it as well but everything's working now.

Thanks again everyone for the help. Electrical issues are such a nightmare...
Good to know though that if the check engine light won't come on it's either a bad bulb or most likely the ecu has a problem.
Old 09-17-2009, 06:01 PM
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Well this same issue has come back to haunt me again. I had it all happen again once last week where the check engine light didn't come on so of course it didn't start. So I pulled the 22P connector and put it back, and nothing. Then pulled the 16p and plugged it back in and it it worked. The check engine light came on and the truck started fine. Today I went to start it up and same issue but this time it didn't fix itself after pulling all the plugs on the ecu and putting them back it. However, when I unplug the 16p connector the check engine light comes on. It runs like crap obviously because, according to the wiring diagram, it doesn't have any input from the oxygen sensor etc. As the trucks running, I put the 16p back in and the engine dies. I've gone through the troubleshooting fsm and measured voltages all over the ecu and haven't found anything wrong. I've tried jumbling wires around to see if it's a bad ground and no success. What might be causing this issue? I seems like it has to be something to do with the 16p connector.
Old 09-17-2009, 07:16 PM
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i'd double check your power lead at the connector itself, and the grounds. If all that checks out, then just replace your ECU and call it a day. You can probably find one in a junkyard for a hundred bucks or so.
Old 09-18-2009, 11:35 AM
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Hi, new member to forums. I too am having the identical problem. The truck is a 93 V6 project car that I bought rolled and replaced with a new cab. I only mention this as I have not done much road testing at all with the car. However, I've driven it around the block a few times and it has been running fine. Finally, after getting all the paper work in order, I took it for a test drive to the gas station to get some gas and on the way home it just died. Cranks over etc.. No CEL, EFI fuse, IGN fuse appear to be fine. IGN + EFI fuse terminals appear to be getting power.

If I pull the 16pin on the ECU, then I get a CEL, and the car actually starts, but runs like crap as mentioned by Tdubbs05.

I happen to have a second ECU that was confirmed to work prior to this incident, but above results are still the same with this part.

I'll keep screwing around and reading up/searching/asking around as much as I can and report back. This is only day one of my problem.
Old 09-19-2009, 05:21 PM
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Update. I tried unplugging the AFM, and the car starts (you need to jump the fuel pump terminals too as the AFM is now "unplugged") + Get CEL. Pulling the 16pin from the ECU has the same effect. putting the pin back kills the engine as Tdubbs05 described.

Does unplugging components mean I have a short somewhere or just a bad AFM? Or possibly some relay associated with it? And what does the 16pin @ the ECU and the AFM have in common?

EDIT:
UPDATE Problem Solved!

Well today I grabbed my multitester and started looking at the specs of the AFM and it was definitely out of whack. Knowing, I'd prob have to replace it, I went ahead and popped the silicone on the cover to have a little look inside....

Apparently a small thin metal tab had broken off of one of the leads and was actually laying across 2 terminals. As soon as I removed the loose impediment, the CEL (Check Engine Light) came on and car started with no problem. (Sort of. I still have my cold start problem as I have a broken water temperature sensor switch which Napa wants 45 bucks for. Or its possible that this broken tab on the AFM has something to do with that as well.)

Here's a picture of the tab shorting out these two terminals. (Circled in red.. a bit hard to see)


Here's a picture of the culprit.


Crazy to think that this little broken tab would keep the car from starting.

It looks like it broke off the 2nd to left lead, but can't seem to decipher where it might go? At any rate, I'm going to get another AFM from the junkyard to compare to and see if I can't repair this one to keep in the car as part of my EFI emergency repair kit. So far I have an extra EFI relay, ECU, ignitor/coil and potentially a 2nd AFM. I think that about covers the EFI, and hopefully I could limp back to civilization with these spare parts. TPS maybe?

Last edited by bajadulce; 09-20-2009 at 11:04 AM.
Old 09-20-2009, 10:04 AM
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I'll check this out and let you guys know what happens. Good find baja!
Old 09-20-2009, 10:38 PM
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Well looks like my nightmare might finally be over thanks to Baja. Looks like we've got the exact same issue at the exact same time. A couple months ago I pulled the AFM our to see what it looked like. In the process I ripped out the contact strips that are soldered to the sensor and the connectors. As you can see in the pics, when I put the AFM back in, it deformed the connector strips and moved them close enough together so that they began to arc which in turn threw the ECU off so it wouldn't start the engine. Here's some pics so you guys and see what I'm talking about:

The arrow points to where they were arcing. You can see how deformed they are.

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Here's what they're supposed to look like but soldered to the board.
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Well hopefully this issues finally taken care of. I knew it was going to be something simple and stupid... I'm debating on whether or not to re-solder them because I might end up making more of a mess if I get solder all over the place. Let me know if anyone thinks otherwise. As of right now the contacts are solid enough and now should be able to touch each other. Everything's running fine now so looks like this problems fixed and now it's time for a little silicone to put that plastic cover back in.

I've learned a ton through this process...maybe a little more than I had hoped but definitely gained a little confidence in my troubleshooting ability. Thanks again to everyone for the help!

Last edited by Tdubbs05; 09-20-2009 at 10:42 PM.
Old 09-21-2009, 08:51 AM
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Wow those pics are really crisp and now I can see where that broken tab of mine came from. Don't know how it broke tho? Maybe a previous owner had unscrewed those screws and tried to pull the circuitry out? Who knows, but I don't wish an EFI problem on my worst enemies, as that was not fun.

I've never had any electrical component fail on any of my fuel injected cars as these things are pretty bullet proof. I'm just happy this happened close to my house with access to this great forum and not out camping in the middle of nowhere.

Ok... On the road again! thnx to all that responded in this thread espc. the guy that suggested pulling the AFM connection and see if we had CEL. Partay time!
Old 09-21-2009, 10:08 AM
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No worries. Glad I could shed some insight.
Old 09-21-2009, 01:02 PM
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The AFM definitely isn't a part that was made to come out and be serviced. Those contacts that I ripped out were supposed to be soldered in for the life of the truck.

I just cant believe this all happened when it did. It'd just be great to shut the runner off while wheeling and have to abandon it out in the middle of nowhere...

Thanks again to everyone and hopefully this helps anyone with this random PITA issue.
Old 09-21-2009, 02:07 PM
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Originally Posted by Tdubbs05
The AFM definitely isn't a part that was made to come out and be serviced. Those contacts that I ripped out were supposed to be soldered in for the life of the truck.

I just cant believe this all happened when it did. It'd just be great to shut the runner off while wheeling and have to abandon it out in the middle of nowhere...

Thanks again to everyone and hopefully this helps anyone with this random PITA issue.
I carried a spare AFM for that exact reason.
Old 01-29-2011, 02:28 PM
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ALRIGHT. THANK YOU THANK YOU THANK YOU. for having this problem. I have been chasing spark for DAYS. replaced my coil, ignitor, efi relay, and so much more work. GUESS WHAT? i had screwed around with the MAF just like you did a few weeks ago and thought nothing of it. i've been researching for about a week now WHEN i finally found this holiest of HOLY threads!!! i had the EXCACT SAME SYMPTOMS and no Check engine light was driving me CRAZY!!! well sure enough same thing happened with me with that metal crossing in the MAF. REALLY THANK YOU FOR THIS THREAD you probably saved me an unbelievable amount of time and frustration =D


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