ECU replacements???

[onecoolkat]

Ive read a lot about this, and steve is the man on this, but I cant seem to match up my numbers to look for a simple replament For...5/88-6/90 - MD128623
E2T34473, and Dont uderstand which others will plug and play nicely , so can some one tell me that info?Still like to send mine to steve to repair, but dont think im sending him e-mails correctly yet...... I/ll try to attach my Pics of the 2 cap's and other damge here.

 

[lasertim]

Try using the PM feature. He is on here enough and I am sure he would be more than willing to help.

 

[onecoolkat]

Update. Auto Computer Exchange in Davie, FL. Had to rebuild my ecu at the tune of 99.99 bucks,( california model and the can not get them I guess) Put it in and Is the very same Cranks But will not start. Iv'e double checked the connections at the temperature sensors and they are connected, still no fuel pump sounds like before this all started, and I think I wanna just Stick some dynamite under the hood at the moment. If any one wants to come look at this feel free, I am running out of reasons to keep putting money into it, Soon to be wife wants to sell me already.

 

[onecoolkat]

I think I need to add some more details, so here I go.
I had just driven this car 2 weeks prior to the "no Start" condition.
There was no stalling, misfiring of any kind, and had 2 week old fill up of the good gas.
As soon as this started the engine would also keep cranking , sometimes as long as 5-7 seconds after I let off the Key. No fuel pump sound as when it ran last,( the right before you start , the little Bizz Chunk from under gas tank) and Even with the Rebuilt ECU have no turbo needle movement, nor 5 seconds of check engine light....So did I get took for a repair thet didnt work, or what to test next?

 

[steve]

Even with the Rebuilt ECU have no turbo needle movement, nor 5 seconds of check engine light....So did I get took for a repair thet didnt work, or what to test next?

Since you blew the main 12v filter capacitor up it would be a good idea to make sure that the MPI fuse on the battery is good. Right now either the ECU is still bad or the power to it is never turning on.

Steve

 

[onecoolkat]

I rem seeing a place where these 2 things are shown, If I am correct the MPI fuse is good as well, can you tell me where the place was that showed whick connector pins should have power at key "on", I have 2 that have power, a red wire, and I think a black with white trace

 

[onecoolkat]

Is there any possibility that the Ignition switch could be playing a part in this? Even though it is actuating the starter motor?

 

[steve]

Yes, a bad ignition switch could cause this but not very likely.
You need the wiring diagram for the MPI circuit or your not going to make much headway.

Here's what I've posted before about diagnosing ECU powerup issues:

The 1G DSM has two main circuits for the engine. The MPI circuit and the Ignition circuit.

The ECU is connected to both but powered from the MPI circuit.

Power for the MPI circuit comes from the MPI fusable link on the positive battery terminal to pin 10 on the MPI relay and should be present all the time even with the car off. Power for the Fuel Pump and the rest of the ignition circuit comes from the Ignition fusable link on the positive battery terminal and for the fuel pump winds up on pin 3 on the MPI relay.

The MPI relay has two actual relays inside, one for the MPI power and one for the fuel pump power. The fuel pump relay has two trigger inputs, the MPI relay one. Pin 10 in the input for the MPI power and pin 3 is the input for the FP power. When one of the control lines to either relay is activated the relay switches the power from the input to the outpin pin(s)

The ECU receives backup power on pin 103 from fuse 19 (room) in the drivers footwell fusebox. This is used to maintain the RAM in the ECU's CPU and allow the ECU to power itself up. Like MPI relay pin 10 the backup power on ECU pin 103 should to present all the time even with the car off.

The ECU sits dormant in a powered down state waiting to see pin 110 (IG1 from ignition switch) go high (to battery voltage). When pin 110 goes high the ECU pulls its pin 63 (MPI relay pin 8) low (to ground). This causes the the relay to activate and switches the MPI power from MPI pin 10 to MPI pins 4 and 5 providing power to the ECU on pins 102 and 107 along with various sensors, solenoids, injectors, ISC, and O2 Heater in the engine bay.

Shortly after battery voltage shows up on ECU pins 102 and 107 the reset circuit in the ECU wakes the ECU up and if it boots up you'll get a heartbeat on ECU pin 1, the CEL will come on for about 5 seconds, the boost gauge will display 0 (Stock ECU software on turbo cars) and the ISC on the throttle body will move in and out to rehome.

The next interesting condition is when ECU pin 108 (indirectly START from the ignition switch) goes high (to battery voltage).

The START signal also goes to the Fuel side of the MPI relay to power up the fuel pump, and to the ECU causing the ECU to do the things it needs to do the start the engine. Once the engine is running the ECU pulls it's pin 56 (MPI relay pin 8) to ground and continues to hold it low until you turn the car off or the engine stops running, to keep the fuel pump powered after you release the ignition.

The first thing you should do if your ECU doesn't power up (CEL on for about 5 seconds, the boost gauge displays 0) is check the two fusable links and the room fuse #19. Measure the fuses for continuity (0 ohms resistance) rather than look at them. Then check for battery voltage at the ECU and MPI relay pins. Remember that the ECU doesn't get power on pins 102 and 107 until the MPI relay is activated by turning the ignition key to RUN or START. If the MPI relay doesn't activate try grounding its pin 8 and check that power shows up on its pins 4 and 5. If that works then either the ECU isn't seeing the IG1 signal or the ECU is damaged.

If power is present on ECU pins 102 and 107, the ECU grounds are good and the ECU doesn't power up it's damaged.


Steve

 

[danyz250f]

Have you checked to see if your car has a remote start/alarm/turbo timer. If so yank that stuff out match the color wires in the ignition harness and solder them back together. You could have a remote start brain that has gone crazy on you. Not likley but worth a look. Just on a side note is the fuel pump plugged in, at the back of the car.

 

[onecoolkat]

Yeah, I crawled under a checked and replugged the wires on the gas tank, and actually put a plug on the spark boot and tested for spark ...but remembered steve saying no turbo gauge movement and no 5 sec. check engine light rule.

I wonder if anyone has a list of what would fit back in this particular model ?

 

[steve]

Is your car a California car like that ECU or did somebody swap the ECU to make the car run.

If it's a California car you can use any of the 4 turbo ECUs from 1990.
MD128623 CA FWD
MD145902 CA AWD
MD128625 Fed FWD
MD145903 Fed AWD

If it's a Federal car or a converted California car you will get a EGR CEL if you use either of the CA ECUs.

By changing the two pins 6 and 14 and installing a 91+ power transistor to provide the ECU with the tach signal you can run one of the 91+ manual transmission turbo ECUs. I've covered this several times in detail in the archives.

If your still not getting the CEL to come on I'd track that down first and make sure the ECU is turning its power on.

Perhaps the company that you had rebuild your ECU can help you out. That's part of what you paid them for.

Steve

 

[onecoolkat]

Thanks this will help in the search...The last guy tested the unit apparently and says the Processor Is Burnt....I cant help but wonder if the first one in Davie FL, had something to do with that/ or If it was just its time to die.
Yes the VIN suggests It is A cali. Car, and The first Buiseness Didnt even Charge my account, the secong guy refunded the charges.
You wouldnt happen to have either one of MD128623 CA FWD,
MD145902 CA AWDlaying around would you?

 

[onecoolkat]

Got a remanufactured one warranteed for 12 months 225 shipped. the md 128623 even...Life Is good again! thx for the support guys.

 

[onecoolkat]

Ongoing Problems.....
Had the "new" ECU in and working fine, everywhere, for about 3 weeks& 5 or 6 trips, Ranging form 10 to 160 mile roundtrip miles. Coming back from the last trip, my wipers, gauges, radio, and all power just dies...all this started by my turning on the radio and it dying like 5 times, then the really bad stuff started...
So I stop and get the hood up, and the Battery is a Maintenance free type, with vents on both sides, and they are just blowing Steam, ( or Smoke) out of them like a broiler. Scared my battery is about to explode, I manage to Unhook the negative cables, and sit for my wife to come with our truck and tow me home.I come on here and search for hours and find many closely related scenarios and beging to close in on the trouble. I have found my battery was dead when trying to start only and showed fine with voltage,(13.74) out of car and 12.34 hooked up. Finnaly put it in my truck and walla, same thing...Ok so one problem fixed. After during, before, who knows the order, , I have cleaned all connections, tested all fuses with light, and Multi meter both, like 3 times over. Got almost everything working now, starts, idles well, eveything excepth the both seatbelt retracting things, and think I have a relay blown, but have lost my book in moving. Also I have some differences in how the car acts form opening door, as well as the actuating of the fuel pump circuit when turning the key to on, just before starting. The door lights work, and dash light for them too, and buzzer/tone. But no noise at all for the seatbelts/retraction system. The charging is like 17.74 at normal idle (650 RPM) and 18 - 19 @2,000 RPM the wierd part is when I turn key to on, the normal 3 to 5 seconds of Whhhhirrr cachunk noise I assume was the Fuel Pump and other things getting ready to start, Happens, but doesnt stop while key is on, like it did before. ANd I have noticed the Little solenoid on top of the Air filter Is what clicks when the batt is hooked up and well as the solenoids on drivers side firewall inlune with many vaccume hoses. I might add that the little soleniod on the air filter cannister is quite warm.
So the question I have is does the ECU controll the retractable seatbelts < or can some name the relay and location for me to check/replace, as well as the wierd non stoping of the initial fuel pump/ all-ready-to-start system, or could the MPI relay have been damaged?

 

[steve]

The charging is like 17.74 at normal idle (650 RPM) and 18 - 19 @2,000 RPM the wierd part is when I turn key to on.

Please don't do anything else with the car until you replace the alternator.
You have a blown voltage regulator. Under no case should the voltage be above 15v.

That fact that you boiled your battery should he been a big clue that the alternator was shot.

Your going to damage the rest of the electrical system if you keep starting the car.

Steve

 

[onecoolkat]

Will do, Or ( not do) Thanks Steve. I have rebuilt altanaters before so is No sweat to do, but I rem trying to get the kit or parts was a big deal at O'rielly's.
Um I forgot a couplke of other observations, there is a relay drivers side kick area, I believe is labeles heater/chauf which seems excessively warm, anything to do with the seatbelts or the overcharging? I may have to send you the Rebuilt ECU yet to check her out, still runs but as you warned, I will not even hook it up till I take care of the Over charging.
Jesus, I have to say I really Loved having her back on the road.