KL ECU is frying! (Solved)

[mazdags94]

Just finished my swap (MTX and K8 to DE). Went to start up today and it cranks but wont turn over (no start). It's getting fuel as I checked, but not sure about spark. When I turn the key to "ON" position, the ECU begins to start heating up and eventually burning (see smoke and that foul odor of burning electronics).

I checked my grounds and everything seems to be sufficient.

Checked my fuses and nothing was popped...

I did notice that on the disty (DE) on the three pin harness, the wires were cracking. I know that theres a 12v source in there but could it be possible that theres a short in or near the coil? I plan to try and cut the 12v wire that goes to the coil to see if it still causes burning in the ecu.

ANyone have any suggestions? I ran out of time to troubleshoot today so I can keep updating as I try things.

The engine is out of a 93 Probe GT, 2.5L DE with PGT MTX, KL07 ECU, KL02 VAF.

My thought is that when I turn the key to "ON" the only things running should be the disty and fuel pump/injectors since the sensors work while the engine is running. If this is so, My problem should be in one area. If need be, I will run brand new wires to the disty. I've spent so much time doing this and I'm getting frustrated at this point.

If anyone could offer any suggestions/pointers, I would appreciate them! Thanks!

Oh, and here is what the K8 ECU looks like now after it burned a little:

[Daninski]

Did you use the disty from your car? What is the PN on the disty your using? What ECU are you using? From like 95 on up the three pin plug on your disty has two wires reversed. At this point I believe you've fried the ECU. Thing is it could be just a flook or it could be your wiring. Give us as much info as you can like what year is your MX3 and the above questions. Cheers

[Nd4SpdSe]

Can you take better pictures of the fried circuitry? If you have a regular digital camera use the Macro setting (usually the Flower button) to allow it to focus on closer items.

[nlsolja123]

my k8 ecu had the same problem...

crank the car and sometimes it would run for a bout 15-60 seconds....mostly it would just turn over but no run... checked fuel and i was getting plenty,,,did hei and come to find out my ecu would not tell the ign control module to spark...ECU=BAD....this is really easy to test when you have hei conversion.... ground the trigger wire and if the coil-dist wire sparks when u do this but no other time u have a bad crank pos sensor hall sensor or ecu is bad

[mazdags94]

Did you use the disty from your car? What is the PN on the disty your using? What ECU are you using? From like 95 on up the three pin plug on your disty has two wires reversed. At this point I believe you've fried the ECU. Thing is it could be just a flook or it could be your wiring. Give us as much info as you can like what year is your MX3 and the above questions. Cheers

The disty I'm using is what came with the Probe GT engine (from a 93). My car is a 1994 GS V6, originally automatic but is now 5spd. The ECU shown in the pics was the K8 as I forgot to change that when I first tried to start it. However, when I hooked up the newer ECU (from the PGT) KL07, it started to smoke a little too but I didn't let it do it for too long so it turned a tiny bit brown but not black like this. As far as the disty PN, I am at work right now but I can get it when I get home. The guy I bought it from said that it was recently rebuilt. I was quite positive that this ECU was done, lol, but I don't think it's a fluke.

Can you take better pictures of the fried circuitry? If you have a regular digital camera use the Macro setting (usually the Flower button) to allow it to focus on closer items.

I will try and get a better picture when I get home. I tried to trace the burnt area to a particular pinout but the black makes it difficult to do it.

my k8 ecu had the same problem...

crank the car and sometimes it would run for a bout 15-60 seconds....mostly it would just turn over but no run... checked fuel and i was getting plenty,,,did hei and come to find out my ecu would not tell the ign control module to spark...ECU=BAD....this is really easy to test when you have hei conversion.... ground the trigger wire and if the coil-dist wire sparks when u do this but no other time u have a bad crank pos sensor hall sensor or ecu is bad

I don't think its an ECU problem since the same area is affected in both the K8 ECU and the KL07. I have a couple other ECU's to use as well as backup just in case but I really dont want to ruin them all. I suspicious of the disty and I plan to check for spark when I get home.

Again, it is getting fuel, but its not turning over. When I turn the key to "ON" without trying to start the car, the ECU starts heating up/burning. That makes me now suspect the coil or something with the disty since the coil is hot whenever you turn the key to "ON".


I appreciate the suggestions guys, and I'll keep you posted with any progress.

[mazdags94]

Just noticed this when pricing out disty's:

1993-1994 Mazda MX6 LS, Mazda 626, or Ford Probe GT equipped with the 2.5L V6. Will NOT fit 95+.

1992-1993 Mazda MX-3 GS with 1.8L V6. Will NOT fit 94+


I am planning on disconnecting the 3 pin harness on the disty and turning the key to "ON" to see if the ECU continues to burn. If not, then I know where the problem is at. I have a feeling that the disty's 3 wire pinout is different than my K8. The seller mentions that the 93-94 Probe GT Disty isn't compatible with a 94 and up MX3!

Is this because of the wiring being different?

EDIT: After doing some searching on here, I am now realizing that the wiring on the 3 pin harness is different for the PGT disty (KLDE) than my original disty (K8). The PN on the disty I had on the K8 was TOT51717, which I found was specific to 94 MX3's. I will try and confirm my suspicions when I get home.

I feel better that I'm getting closer. I hope that the 3 pin harness is the only one that is wired differently....

[Daninski]

As 94 is a different animal I wasn't sure if the 3 wire disty plug was different on the 94. If your not sure which wires you need to switch I can tell you once I get home tomorrow. 92-93 used the cam sensor but I don't belive that would cause a problem in fact Mega Squirt says if you don't have a cam sensor you need to use a disty that has one.

[mazdags94]

If you could tell me, I would greatly, greatly appreciate it! It would save me days of testing wires!!! I did some testing yesterday but I have to leave for work so I will post them later. My wire sequence for the 3-pin harness is (starting from the radiator side) Blue (tested hot when ignition turned on), Red, and then Yellow w/blue stripe.

[mazdags94]

So heres where I'm at:

- I'm getting fuel

- I'm not getting spark

- I pulled the three pin harness and put the ignition to "ON" position and ECU was fine so it seems to have something to do with those wires since it is only sending power to the coil and fuel (as it should on startup).

I tested the 3-pin harness inputs while unplugged, with the ignition in the "ON" position, and found:

Yellow/blue wire - Cold
Red wire - Cold
Blue wire - Hot

I also tried a few connections to find the power wire of the ECU:

Firewall Side

3-pin harness:____________ Disty input:
A- Yellow/Blue .....................................1
B- Red .................................................2
C- Blue ................................................3

Radiator Side

Using the above diagram, I've connected:
- C to 3, B to 2, A to 1, --> ECU burn (stock harness configuration for previous 94 K8 disty)
- C to 1, B to 3, --> ECU burn

If I knew what the pinout is for the KL disty, I could try and match them up correctly. I have researched several HEI mod threads to check wiring diagrams but I'm at a point of confusion...

The PN on my 93 PGT V6 disty reads - "2007071301" (the last few digits I'm not clear on since I dont have my notes with me, I forgot them at home)

I will again say that I had the "very specific" 94 disty on my k8, (which was sold) so the wiring, from my understanding is different as you suggest Daninski (I'm pretty sure anyway).

[Daninski]

I can't get you that info till Saturday, I need to go out to the garage. I can compare a 92 to my 96 and that will tell us which wires are reversed unless someone on here right now can go out and check their disty for you.

[mazdags94]

That's fine, I would appreciate it. I can test some wires for shorts and such just in case. I also discovered that I have a KL90 ECU, OBDI, which should override the extra coolant sensor problem. I really dont wanna cook that one so I'm not hooking that up until I know I fixed the problem. Would any of the wires on the 6-pin plug (on the disty) be switched around?

Once I can get spark, she should start, then I can get the idle under control and troubleshoot any code errors. I'll be hitting the 3rd year anniversary of my date of purchase on this car and it hasn't been on the road at all. I did drive it around with the K8, but I'm really anxious to try my DE.

[mazdags94]

I'm starting to think that I should have kept my 94 disty......

[wytbishop]

If you can find a pinout diagram for the ECU you want to use and compare the pins to the MX-3 pinout diagram you should be able to tell if the disty 12V wire is in the right location with your combination. If you use the DE ECU and the DE disty, you just have to make sure htat the MX3 harness routes the right wires to the right ECU pin. It's easy enough to relocate a wire.

I'm sure I've read about this before. Buring up that transistor because the power wire for the disty is on the wrong pin for that ECU.

Your biggest problem is having a 94'. The ECU and pinout is different from all other years I think and the online manuals won't be correct for you. Call your local Mazda dealer and ask the service manager if he can get that for you. if you talk nicely to them they can be very helpful.

[mazdags94]

Traced the wires and they are where they need to be as far as the ECU harness but I don't think the disty input lines up with input harness (3-pin of course). Blue is 12V+ and Red is 12V-, where it should be on the ECU harness/pinout.

I just need to find a pinout diagram of a 93-94 PGT V6 disty pinout chart for the distributor (3-pin and 6-pin) so I can compare the MX-3 to the PGT wiring...

Anyone have access to this?

[mazdags94]

Update....9-8-09:

switched wires around on my 3-pin disty harness and KL07 is no longer frying. Still Won't start...

Using my above diagram, my new configuration is as follows:

FIREWALL SIDE

Blue (12V+)

Yellow/Blue (Tach)

Red (12V-)

RADIATOR SIDE

Tried a KL90 ECU and it fried that one (I think it's because the pinout is different).

Gonna see if I can pull codes using the KL07 ECU.