90 Eclipse GSR4 repaired ECU diagnosis

"Bornish" schrieb im Newsbeitrag news: snipped-for-privacy@localhost.talkaboutautos.com...

located, many cars are coming from Japan)

and the ECU burned while driving, luckily in second gear at ~30 km/h.

the PCB and repair the hole in the PCB :) since I could not find a second-hand replacement anywhere.

Hard to say , if there haven't been other components as well which may be blown as a cause or a result of the burning.

considering the price I paid for the entire car, is out of the question.

I can hear & feel a repeately short combustion as long as I keep trying to crank it.

(I'm a software developer, so I believe them)

and conectivity.

ON, and a variating 10-12 V while cranking.

As I understand this are open circuit measurements. It may well be, that the driving circuit can not pump the necessary current, if it sees the low impedance of the injector coils. An overheated power stage may have been the primary cause for the ECU to get in fire.

testing values to make on the board, I cannot be sure if something else got damaged.

The best way to get more informations would be to connect a scope in parallel to the injectors, to see the impulse shape and duration at the coils. You further should check the fuel pressure, which should be about

1,8 - 2 bar with the throttle in starting position ( almost closed). Remove the plugs after you have cranked the engine for a reasonable time. They should be wet after all. If not the injectors haven't properly opened.

and that's a good reason for me not spending money on another ECU, until I'm sure mine is not functioning correctly.

If the above mentioned tests seem to deliver appropriate results, it still may be that the injector pulses are out of phase with the ignition sparks. This can be due to a problem with the crank- or camshaft sensor or the corresponding circuit on your PCB.

Marcel Baum

located, many cars are coming from Japan)

the ECU burned while driving, luckily in second gear at ~30 km/h.

PCB and repair the hole in the PCB :) since I could not find a second-hand replacement anywhere.

considering the price I paid for the entire car, is out of the question.

can hear & feel a repeately short combustion as long as I keep trying to crank it.

software developer, so I believe them)

conectivity.

and a variating 10-12 V while cranking.

testing values to make on the board, I cannot be sure if something else got damaged.

that's a good reason for me not spending money on another ECU, until I'm sure mine is not functioning correctly.

Hi Tony! I've just found the manual of my car on

and bought it. Since not all DSMs are having the same trouble codes and same configuration of the diagnosis port, and because my car doesn't start makes it complicated to get it to a garage which has a proper scan tool, I don't have yet an error code. Moreover, since the ECM (ECU) was damaged, I would not trust too much a trouble code of a possible faulty board. I am still planning to connect a multi-use tester to the diagnosis port, now that I have the correct way of doing it. As I read in the manual, there are lots of condition to be met previously the code extraction, in order for it to be correct. The wiring seems very complicated and must be checked before installing a new unit, to ensure that will not get damaged. Thanks for posting, and if you have some experience with code interpretation, please share it, because I'm sure I will get stuck again after reading one from a repaired unit. Please remember that I'm not even an electrician and I didn't have a scheme when trying to repair the damage. What I can tell you is that I found a site where the repair routine was nicely described & luckily the pictures were of the same circuit board. So, at least I know that what I did was not wrong, but not necessarily sufficient. I promise to post again as soon as I will have more details.

Marcel, please excuse my rush when I've posted. I'm so happy to find ppl trying to help me. I'll tell you the whole story as much as I know it. I don't have the technical history of the car, so many infos may not be actual facts but observations of an unexperienced driver (me). All seems to be original on the car (no modifications), which was maintained quite good by the previous owner. Since I bought the car (8 months back) I've changed the front axel boots, the oil in the gear boxes, topped the coolant, changed the oil every 3000 km, filled with gas and washed it :) I was very happy driver, but I was wrong. Ever since I bought it, the car randomly and rarely failed to start from the first try, when the humidity was very high or the car stayed for a couple of days in the parking. I thought was normal for an old car, or at least ok. Wrong! Moreover, I've ignored other symptoms like engine stalling after it started, and once, even after about 1 min. after I've started driving. That was the time to take out the ECU and check the electrolytic capacitors for leaks, and replace them after cleaning the board. But I didn't, misinterpreting the symptoms as many others, as I read later on the internet. One day it happened: the leaks made enough corrosion on the circuit board creating the short that "killed" my car, as I described in my first post. Was no use to check the fuses or try starting the engine. I've even seen a small thread of white smoke coming from the dash-board. From the sound and the smell, I knew that was an electrical short. The car was craned to my friend's garage, and the ECU was removed and opened. I've started looking for a replacement and at the same time research on internet for possible causes, etc. I was also afraid to try a new one which could've been damaged if the cause was not "inside that box" :) But, as much as I've tried, I couldn't get one that at least matches the number of pins, not saying about the product code. Next try was to order a used one on the net, but all answers were "Sorry, we don't have it in stock". Only Foreign Auto from Tampa replied possitive on rebuilding mine but when I put some delivery & warranty questions they replied too briefly: "CALL ...", so I lost my trust. In the meantime, I've decided to try myself rebuilding it. My appologies for making you read so much, but I'm almost done now :) Went to the garage and test it: - spark is coming on all 4 plugs (don't know if timing is correct, yet) - fuel comes on the pipe when cranking, so I assume the fuel pump works (also got repeatedly combustion for a fraction of a second) - didn't measured the fuel pressure with a gauge as supposed to, but the mechanics said "looks ok" - suplying the engine with fuel directly, the engine runs (with incorrect combustion, of course); we did a short test only - suplying the injectors with fuel from a can, engine doesn't start; our guess will be all injectors are staying closed - plugs were removed, cleaned, but no sign of being wet, so again we guess no fuel cames from any injector. - checked the wiring for connectivity, resistance & supplied voltage, but I had no data to compare with (only today I found some in the manual I bought from

- a couple of relays I found were checked and passed, but I'll post again after checking all mentioned on the electrical diagram (I would bet on the noise filter) I am really appreciating your help and patience. I hope is all more clear now and is making sense. Many thanks, Bogdan

Bogdan,

It seems as if the engine was running on the weak side from the very beginning . You may either find a low fuel pressure (its essential that it reaches the pressure I have mentioned in my last reply) or you may have troubles with the starting solenoid valve . I would not rely in just seeing that fuel is pumped, the fuel pressure regulator may have a broken membrane and you will still have flow under open conditions but no sufficient pressure to overcome the injector nozzles.

The following links are dealing with different BOSCH EFI systems , but even so Mitsu doesn't use Bosch, it seems to be a license production of a Japanese brand. So you definitely will find similarities between both systems

In you will find a bench testsetup for the EFI , however I am not sure the pin layout is the same youhave.

As long as you haven't checked whether the power stage of your ECU is really capable to open the injectors and your fuel pressure is OK its really hard to come to a better conclusion.

"Bornish" schrieb im Newsbeitrag news: snipped-for-privacy@localhost.talkaboutautos.com...

actual facts but observations of an unexperienced driver (me).

maintained quite good by the previous owner.

the oil in the gear boxes, topped the coolant, changed the oil every 3000 km, filled with gas and washed it :)

the first try, when the humidity was very high or the car stayed for a couple of days in the parking.

started, and once, even after about 1 min. after I've started driving.

capacitors for leaks, and replace them after cleaning the board.

on the internet.

creating the short that "killed" my car, as I described in my first post.

internet for possible causes, etc.

cause was not "inside that box" :)

number of pins, not saying about the product code.

we don't have it in stock".

I put some delivery & warranty questions they replied too briefly: "CALL ...", so I lost my trust.

(also got repeatedly combustion for a fraction of a second)

mechanics said "looks ok"

combustion, of course); we did a short test only

guess will be all injectors are staying closed

guess no fuel cames from any injector.

I had no data to compare with (only today I found some in the manual I bought from

after checking all mentioned on the electrical diagram (I would bet on the noise filter)

Hi I have more news about my car, still not fixed though. I couldn't pull any diagnostic code... the ECM is still faulty. I've measured the injectors's resistance and were not damaged (lucky me). I've read on

how to check the harness wiring to be sure I'll not damage another unit if installed. Since I could not find another ECU, and in this country nobody wants to be responsable of rebuilding it, I had to try to repair it again. Each injector is directly connected to ECU through 2 wires. /-------\ | 1 | 2 | \-------/ No 1 goes to the same pin, probably being the ground. Having 5 pins to pulse the injectors, the ECU uses 5 transistors sticked on it's radiator for this purpose. Took them all out from the board and the one connected to the "ground" stays opened at all times. Must be destroyed. I hope it's my last problem. Was located near the capacitor blown-up. It seems that the short made possible a high intensity current to flow through it's base and damage it. Unfortunatelly, was not on stock on the shops I've been. I'm sharing my experience with you because it may help somebody else facing someday the same problems. Please DO NOT IGNORE any symptoms that your car may show. I've learned this lesson in the hard way. If anyone knows a good forum about electronics, please share. Thanks for reading, Bogdan

can hear & feel a repeately short combustion as long as I keep trying to crank it.

software developer, so I believe them)

You better bet the injectors are pulsed by the ECU! (I'm a computer scientist and a) don't belive my mechanics friends because we're talking about electronics here, b) wonder what else might pulse the injectors besides the *engine control* unit and c) know better, check the ECU pinouts:

vfaq.com has manymore on Mitsubishis...) Norman

combustion, of course); we did a short test only

IMHO this should have fried your catalytic converter, right?

Norman

In my understanding, you can *always* pull an error code from the ECU - if it's a constant signal, the ECU reports an ECU error, which it even does when it's not running at all. You should check that first - if you don't get a signal on the ECU status port at all or a constant signal you shouldn't worry about anything than the ECU in the first place.

Norman

The injectors are tied to the ECU individually and are commoned to the MPI (+ 12 volt) relay. The ECU provides a ground when it wants the injector to inject fuel, it definitely is pulsed. Timing is very important, have you checked the dist output signals.

Quiet right, if you don't get the right signal from the ECU, look there first. Constant high signal on the error output lead is a failed ECU, no output on the same lead is also a failed ECU. Normal is a steady pulse output. Failed to me means it's not working, could be because of a blown fuse, etc., external to the ECU.

You're right, I got a constant signal. This is what I meant by having no signal. Sorry for the misunderstanding. I am in fact checking only the ECU and it's wiring. Biggest problem is that I could not find a replacement which I can afford (a new unit costs about $1000 and I bought the car for $2200) and that's why I have to fix my unit, if possible. I really appreciate your help.

I've read almost all on vfaq... great link, thanks. Sorry again for a misunderstanding: the mechanics were saying that there's no pulse to the injectors, but should be. This is what I meant by "injectors are not pulsed by the ECU". Since I don't have an osciloscope available, I could not check if there is pulse or not, but I believe the mechanics and the question is why. The board didn't show any fault after the first repair, so I've double checked all the harness wiring. Later, I've removed 5 transistors: - first 4 are connected to GROUND (pins 101 & 106) and each injector (pins

51,52,60,61), but using a MUT, they all seem to function correctly - the 5th one is connected to Power Supply (pins 102 & 107) and many components on the PCB, including the EPROM This one is not giving response to a MUT and I believe was damaged. Shops arround are not having it in stock. No equivalent available, too. The weird part is that I'm getting power to all injectors, but GROUND. Would've make sense if first 4 MOSFETs (transistors) were connected to power and the fifth to GROUND. I'll try making the scheme of the board using Visio or something. This is becoming more complicated than I thought. Thanks for all your input. Talk soon, Bogdan

Hi Nirodac. Every thing you said is correct. My ECU is giving constant signal because is not working properly. Do you think those 4 transistors (reffer to my reply to Norman) are supposed to be signaled when each injector should be grounded? My tests are saying these transistors are functioning and that would mean the microprocessor is not signaling them. Do you think is possible for the processor to not signal because the fifth transistor which I found faulty is not giving enough power supply? I've noticed that a small filter is installed in parallel with this transistor. It's unbelievable but in this whole country there's nobody able to fix this. Most of the ppl have no idea about what I'm talking. I really miss my country... :(

"Bornish" schrieb im Newsbeitrag news: snipped-for-privacy@localhost.talkaboutautos.com...

no pulse to the injectors, but should be.

pulse or not, but I believe the mechanics and the question is why.

checked all the harness wiring.

(pins 51,52,60,61),

components on the PCB, including the EPROM

Which component deliveres the input signal to this transistor. Is it directly connected to a processor pin or can you find a driver circuit for it? Can you give us the type of transistor you are looking for? I dont see that it should have specs which could not be handled by any modern standerd PWR transistor.

power and the fifth to GROUND.

(pins 51,52,60,61),

components on the PCB, including the EPROM

What is the part number? I could probably suggest a good replacement...

power and the fifth to GROUND.

Not that complicated :) it is a very common arrangement, the injectors are all supplied 12V from the main MPI relay and those 4 transistors switch the other side of each to ground to pulse them.. The fifth transistor is part of the main +5V regulator for the ECU i believe...

I have one of these ECUs in my car, did the caps a couple of years ago but I may pull it out again to familiarise myself with it :)

-Richard (electronics tech)

Hi Bornish Just a curious question, what country are you in?

The following information applies specifically to ECU part number MD159561, from a 1991 Plymouth Laser (Eclipse), non turbo. I'm giving you this information because I believe it to be close to your ECU, if nothing else, it'll give you some insight into how the Mitsu ECU's are built.

Looking at my ECU from my 1991 Eclipse (Ply Laser) the green power transistor near the center of the circuit board is a 2SB1335A, PNP, Vceo=80V, Vcb=5V, Ic=10 Amp, and power rating is 50 Watt. It subs to an NTE

378. This is nothing fancy, it's rated an audio power amp transistor. The other four transistors are part number (all 4) 2SD1415, NPN Darlington, 100V, 7A, 30 watt. These transistors provide the ground to the injectors, when the ECU wants gas injected into the cylinder. By the way just incase you have different transistors, remember the Japanese drop the first two characters on the device number. Example 2SB1335A will be printed as B1335A on the transistor.

Check out the circuit trace at both ends of capacitor C4. C4 is located at the anode (non banded) end of the big diode in the center of the PCB. One side is the ground feed the other side is the 5 volt feed. There should NOT be a break in the trace on the +5 volt side. C4 is a tiny surface mount cap. Check very closely with a magnifying glass. Scrap off any protective coating if necessary. If you can power up the ECU with the cover off, you should be able to measure +5 volts at the center pin of the green (2SB1335A) power transistor, the negative of the meter is grounded on the anode side of the big diode in the middle of the PCB. This is the five volt regulator output. BEWARE, if you slip off this pin with your probe and short an adjacent pin,you will most likely toast the ECU. Remember that there may be a conformal coating on the PCB. You should be able to follow this trace right to the other end of the PCB and around to pin 42 of IC2, the second biggest chip on the circuit board. I think also that pin 43 of IC 4 (the big one) is also at 5 volts from this rail. There should be 5 volts at all points on this trace

If your processor is not getting the 5 volts it needs to run, it will not be able to pulse the injectors, or do anything else for that matter. You should replace ALL your filter capacitors just on spec. This is a real issue with Mitsu ECUs.

Remember also that this information refers to a specific ECU, while it may also apply to your ECU, it also may not.

Good luck, and keep us posted.

is not working properly.

supposed to be signaled when each injector should be grounded?

the microprocessor is not signaling them.

transistor which I found faulty is not giving enough power supply?

this. Most of the ppl have no idea about what I'm talking.

Hi Nirodac,

thanks for that posting! That helped me a lot with my problem (see "1992 Galant ECU Problem or not?"). Do you know the exact value of C4? During desoldering my cap was damaged (or by the electrolyte spilled over it), so I can't get its exact value (a LCR meter will read 15-50 nF), but I need to replace it. I you don't now its exact value, I'm still now sure what the function of C4 is - maybe you can tell me and I get a better hint of what capacity to guess at.

Thanks, Norman

C4 appears to be a bypass capacitor. It's positioned between the +5 volt rail and ground. Not critical in value, my guess is most likely .01 uF, but it could also be .1 uF, at about 20 volts. It's not marked on mine. For testing purposes you could run without it. Just why did you unsolder it. If the trace was broken you could have just placed a jumper wire across the break.

Nirodac

It's parallel to C104 (a 100uF electrolyte cap) on mine - that's why I was wondering what C4 is for. C104 is there to stabilize the power suppy (the +5V rail), that's how far my somewhat limited knowledge of electronics brought me. I still can't figure out what C4 is supposed to do - filter freuquencies or what?

Sigh. It's not marked on mine either. Just who had the smart idea of not marking ceramic SMD capacitors? So I'll have to take a wild guess at the capacity and hope operation will be stable. (I'm probably going for 0.1 or 0.033 nF because my local electronics dealer only stocks those two in that capacity range and I'm not up to ordering anything else. And bigger is better, anyway.)

The trace wasn't broken. I had 5 V on one side (towards the transisitor), but about 3,5 V (dropping to under 3V during load) on the other side (towards the ICs). It was either a bad connection with a resitance or a "short" (with some resistance) to ground. Because C4 had been covered with electrolyte, it was somewhat corroded and had electrolyte _under_ it - probably "shorting" C4. Since I've desoldered more than SMD component in my life I figured it to be safe - just take C4, clean everything, measure C4 with a LCR meter, buy a replace, solder it, happy car again. I think the bondings of the SMD cap have been somewhat corroded by the electrolyte, that's why I didn't come off undamaged.

By the way, thanks *a lot* for your help! Norman