BRAT ECM - Possible Problem...?

[DonCordier]

Howdy,

 

I am seeking advice or suggestions regarding a possible ECM problem that I may be having with my BRAT.

 

I have a 1983. It was manufactured very late in the year of 1983. Its VIN is: JF2AT55B9DF502996.

 

This vehicle is equipped with the original factory 1.8 Liter, Turbocharged and Fuel Injected (MPFI) engine and was originally sold in Los Angeles. Thus it has all of the original California Emissions Equipment and the original automatic transmission too. Even though it was manufactured late in 1983, it is equipped as if it were a 1984 model year.

 

I believe the ECM is giving me problems as it began to be intermittent on starting and recently will not start at all. I have tested all of the related components and it appears that the "trouble" may be in the ECM. The Part Number of the ECM is 42089 7320. My initial question is - is it possible to have this unit tested? If not possible to test, does anyone have any recommendations regarding purchasing a replacement ECM?

 

Better yet, does anyone in this forum have a unit that they are willing to sell? If so, please e-mail or call me direct.

 

BTW - All fusable links, fuses and connections are good too. Also, there is no corrosion at any connector/connection throughout the wiring harness.

 

Thank you in advance for the courtesy of your reply.

 

Don Cordier

Simi Valley, California USA

TEL: 818-400-2848

[McDave]

Any auto parts store can order a remanufactured ecm for you. Here's what the ones sold at NAPA have to say about them...

 

"Features & Benefits 100% Full-function, Computer Tested Under Simulated Engine Environment. Ensures Unit Functions Properly Under Real Life Conditions.; 100% Resolder Of Critical Components. Ensures Superior Electrical Connections, No Intermittent Failures And Longer Product Life. Attributes Flash Reprogramming : Yes

Level of Quality : Meets Or Exceeds OE Specifications.

Warranty 12 Months/18,000 Miles, Replacement Will Be Issued for the Vehicle on Which It Was Originally Installed. Extended Only to the Owner of the Vehicle-Not Transferable. See Complete Warranty Statement for Details. Material Safety Data Sheet (MSDS) There is no MSDS for this item."

 

BTW... even though it was built in 1983, your car is an '84. All manufacturers start their model year in August and date them the following year... generally, there are exceptions.

[GeneralDisorder]

BTW... even though it was built in 1983, your car is an '84. All manufacturers start their model year in August and date them the following year... generally, there are exceptions.

 

That's not neccesarily the case. The grill will give it away... the 83 would have straight horizontal louvers, and the 84 would have a honeycomb.

 

Aside from that your problem is almost certainly not the ECU. ECU failures in Subaru's of any vintage are virtually unheard of. Beleive me - you don't want it to be the ECU either. The EA81T was only made for two years and is an extremely rare engine.

 

What symptoms lead you to this conclusion? Just because it won't start?

 

Does it crank? Do you have fuel? Spark?

 

GD

[DonCordier]

Hi "McDave",

 

Thank you for the good information. I have a local NAPA store (with a bunch of "old timers") here in Simi Valley. They always seem to be able to assist in solving problems but I forget to go to their place as it is much further away than some of the pats stores that I often use. I will check with them for the ECU plus some information on the Control Unit that is within the distributor. I do not have any information as to "how" to test this particular item.

 

If you happen to come up with some other thoughts or suggestions, I will certainly welcome your input and efforts.

 

Best wishes,

 

Don Cordier

Simi Valley, California USA

TEL: 818-400-2848

 

Any auto parts store can order a remanufactured ecm for you. Here's what the ones sold at NAPA have to say about them...

 

"Features & Benefits 100% Full-function, Computer Tested Under Simulated Engine Environment. Ensures Unit Functions Properly Under Real Life Conditions.; 100% Resolder Of Critical Components. Ensures Superior Electrical Connections, No Intermittent Failures And Longer Product Life. Attributes Flash Reprogramming : Yes

Level of Quality : Meets Or Exceeds OE Specifications.

Warranty 12 Months/18,000 Miles, Replacement Will Be Issued for the Vehicle on Which It Was Originally Installed. Extended Only to the Owner of the Vehicle-Not Transferable. See Complete Warranty Statement for Details. Material Safety Data Sheet (MSDS) There is no MSDS for this item."

 

BTW... even though it was built in 1983, your car is an '84. All manufacturers start their model year in August and date them the following year... generally, there are exceptions.

[cobcob]

Starter switch on the fritz? Will it crank but not start or not even crank?

[DonCordier]

Hi "GD"

 

You are correct! 1983/1984 was one of those "transitional periods" for Subaru. My 1983 was manufactured in April of 1983 which is right near the end of the production run for the year (usually August of previous calendar year through about the end of May or early June of the current calendar/model year. The production sequence number is "02996" (VIN JF2AT55B9DF502996).

 

Mine has the conventional valved (not an OHC) 1.8 engine with factory turbocharging, MP Fuel Injection, automatic transmission with Single Range 4WD, air-conditioning, power steering, etc. (lots of options). Also, you are a good observer as it too has the "honeycomb" grille!!!

 

Regarding your questions, it cranks exceptionally well but it does not have "spark" or any signal to the four separate fuel injectors.

 

I did test the fuel pump (separately) and it works well. The fuel pressure is right in the book range too.

 

I did open and re-close all of the connectors beneath the instrument panel. There was no signs of corrosion nor any indication of overheating at any of the connectors (like my '91 Legacy heater relay!!!).

 

I have done all "known" tests of the ignition system including the coil primary and secondary circuit tests. Also, used a noid light on all four fuel injector connections and no current or pulsing was observed at any of the four units.

 

The starter solenoid wires are clean and tight and I tested the continuity of all harness wires that I could access.

 

One problem may be the distributor Pick-Up CU that is within the distributor. I did not have any information available to test the Pick-Up Coil and Control Unit. Do you happen to have any knowledge or suggestions as to "how" to test this part? FYI - The only reference material that I have for the BRAT is the Haynes Manual for the 1980 thru 1989 Subaru 1600 and 1800 vehicles. This book also includes the supplement for revisions and special items for the 1984 and later models.

 

BTW - I went to a local parts store that has access to lots of older Subaru items but the only distributor control unit that they can get is a “two-wire” unit. The one in my BRAT is a “four-wire” unit??? Hmmm...???

 

FYI - My car has not ever had any electrical problems. It has absolutely no corrosion within any harness connector or ground in the electrical harness and has not accidentally suffered from any electrical shorting to the best of my knowledge. This evidence will speak well for having been sold new in West Los Angeles and either kept there or in Simi Valley for its entire life.

 

Even though I totally agree with you that I do not want it to be a ECM, I am at the point that it appears to be the only possibility - other than the Distributor Control Unit.

 

If you have any additional ideas as to other items to check I will certainly welcome your added suggestions.

 

Best wishes,

 

Don Cordier

Simi Valley, California USA

TEL: 818-400-2848

 

That's not neccesarily the case. The grill will give it away... the 83 would have straight horizontal louvers, and the 84 would have a honeycomb.

 

Aside from that your problem is almost certainly not the ECU. ECU failures in Subaru's of any vintage are virtually unheard of. Beleive me - you don't want it to be the ECU either. The EA81T was only made for two years and is an extremely rare engine.

 

What symptoms lead you to this conclusion? Just because it won't start?

 

Does it crank? Do you have fuel? Spark?

 

GD

[GeneralDisorder]

Hi "GD"

 

You are correct! 1983/1984 was one of those "transitional periods" for Subaru. My 1983 was manufactured in April of 1983 which is right near the end of the production run for the year (usually August of previous calendar year through about the end of May or early June of the current calendar/model year. The production sequence number is "02996" (VIN JF2AT55B9DF502996).

 

Mine has the conventional valved (not an OHC) 1.8 engine with factory turbocharging, MP Fuel Injection, automatic transmission with Single Range 4WD, air-conditioning, power steering, etc. (lots of options). Also, you are a good observer as it too has the "honeycomb" grille!!!

 

Even though they are rare, we are quite familiar with your engine (I've owned two of them). It's nothing entirely out of the ordinary as Subaru continued on with a turbo system almost identical to yours from 85 to 90 using the EA82 engine - which is essentially the same but with overhead cams. The grill makes it an '84 model year.

 

All EA81T's were automatic, and all of them have hydraulic lifters. The block is a normal EA81 with dished pistons to reduce it's comp. ratio, but the heads are quite special as they have injector bosses built into them. All Turbo Brat's were equipped with power steering and most of the other options (but not power windows ).

 

If the original turbo hasn't been swapped out for an EA82 style water cooled turbo you should do that - it was a factory recall during the mid 80's as the oil-only turbo's were not reliable. You can pretty easily retrofit an EA82 turbo and run the coolant lines appropriately.

 

Regarding your questions, it cranks exceptionally well but it does not have "spark" or any signal to the four separate fuel injectors.

 

I did test the fuel pump (separately) and it works well. The fuel pressure is right in the book range too.

 

I did open and re-close all of the connectors beneath the instrument panel. There was no signs of corrosion nor any indication of overheating at any of the connectors (like my '91 Legacy heater relay!!!).

 

I have done all "known" tests of the ignition system including the coil primary and secondary circuit tests. Also, used a noid light on all four fuel injector connections and no current or pulsing was observed at any of the four units.

 

The starter solenoid wires are clean and tight and I tested the continuity of all harness wires that I could access.

 

One problem may be the distributor Pick-Up CU that is within the distributor. I did not have any information available to test the Pick-Up Coil and Control Unit. Do you happen to have any knowledge or suggestions as to "how" to test this part? FYI - The only reference material that I have for the BRAT is the Haynes Manual for the 1980 thru 1989 Subaru 1600 and 1800 vehicles. This book also includes the supplement for revisions and special items for the 1984 and later models.

 

BTW - I went to a local parts store that has access to lots of older Subaru items but the only distributor control unit that they can get is a “two-wire” unit. The one in my BRAT is a “four-wire” unit??? Hmmm...???

 

FYI - My car has not ever had any electrical problems. It has absolutely no corrosion within any harness connector or ground in the electrical harness and has not accidentally suffered from any electrical shorting to the best of my knowledge. This evidence will speak well for having been sold new in West Los Angeles and either kept there or in Simi Valley for its entire life.

 

Even though I totally agree with you that I do not want it to be a ECM, I am at the point that it appears to be the only possibility - other than the Distributor Control Unit.

 

If you have any additional ideas as to other items to check I will certainly welcome your added suggestions.

 

Before you go through that, please yank out the passenger seat and check the ignition relay. It supply's power to the ECU on pin 24 and if it's on the fritz everything will go dead. Check that it clicks when you energize it and check for continuity through the contacts.

 

GD

[DonCordier]

Hi Rick,

 

Yes, it is apparent that you know a lot about this vintage Subaru option; Turbocharged, 3-speed automatic, air-conditioned, MPFI (requiring the FI machined bosses in the heads), hydraulic lifters and lowered compression pistons were the only way this package was offered.

 

No, I still have the non-water cooled turbo (original). Sheeeeeesh! It only has 205,000 miles on the motor. Goes to illustrate what oil, oil filter and air filter servicing on a "too frequent" basis will do for the motor. The real key though is to never overheat the engine! While it has not happened on my BRAT, my '91 Legacy L had a radiator failure (once) on the freeway about five miles from my home. As soon as the temperature began to rise rapidly, I pulled over and shut it down. I called for a flat bed even though it was slightly less than five miles to home. A person can easily be tempted to "nurse" it home but... I pay for the best AAA Road Service as-well-as have a breakdown reimbursement on my auto insurance. It is not worth pushing things as it will always cost a lot more in the long run.

 

BTW - My Legacy L has been with me since new. It is a FWD only (kinda' unusual) but the tradeoff is it is somewhat lighter than the 4wd or AWD versions of this same model. Thus it gets somewhat better mileage. I have driven it to Coeur d'Alene twice (at speeds I will not admit herein!!!) on US 395/US95 and averaged 33 mpg on both round-trips. The "best" I can do in the '01 Outback Limited is about 27mpg.

 

I worked on the BRAT today but still have not been able to solve the "no start" problem. I am curious what you may think about the Ignition Control Unit? I am not familiar with any test for this item except for installing a known operable unit. The problem is that I have not been able to locate a replacement unit to purchase. The reason is that there was a special Hitachi Distributor and ICU plus an ECM and harness compatibalilty issue on cars originally sold in California (it has 4-wires on the ICU) and all of the ICUs or Modules that I have located are 2-wire ONLY and specifically NOT offered installation in California vehicles. Beides the California requirement, I do not know if a 2-wire unit would work anyway?

 

Gotta' go for now.

 

Thanks again for your comments.

 

Best wishes,

 

Don Cordier

Simi Valley, California USA

TEL: 818-400-2848

Even though they are rare, we are quite familiar with your engine (I've owned two of them). It's nothing entirely out of the ordinary as Subaru continued on with a turbo system almost identical to yours from 85 to 90 using the EA82 engine - which is essentially the same but with overhead cams. The grill makes it an '84 model year.

 

All EA81T's were automatic, and all of them have hydraulic lifters. The block is a normal EA81 with dished pistons to reduce it's comp. ratio, but the heads are quite special as they have injector bosses built into them. All Turbo Brat's were equipped with power steering and most of the other options (but not power windows ).

 

If the original turbo hasn't been swapped out for an EA82 style water cooled turbo you should do that - it was a factory recall during the mid 80's as the oil-only turbo's were not reliable. You can pretty easily retrofit an EA82 turbo and run the coolant lines appropriately.

 

 

 

Before you go through that, please yank out the passenger seat and check the ignition relay. It supply's power to the ECU on pin 24 and if it's on the fritz everything will go dead. Check that it clicks when you energize it and check for continuity through the contacts.

 

GD

[GeneralDisorder]

I worked on the BRAT today but still have not been able to solve the "no start" problem. I am curious what you may think about the Ignition Control Unit? I am not familiar with any test for this item except for installing a known operable unit. The problem is that I have not been able to locate a replacement unit to purchase. The reason is that there was a special Hitachi Distributor and ICU plus an ECM and harness compatibalilty issue on cars originally sold in California (it has 4-wires on the ICU) and all of the ICUs or Modules that I have located are 2-wire ONLY and specifically NOT offered installation in California vehicles. Beides the California requirement, I do not know if a 2-wire unit would work anyway?

 

Looking over my wireing diagrams I think the component you are refering to is the ICU for the knock control unit. The ICU interfaces with the knock control unit to allow control over high-altitude spark advance. Above 1400 feet elevation it advances the timing by 5 degrees apparently.

 

It is seperate from the ECU though, so I wouldn't think the operation of it would affect your fuel delivery unless the ECU wasn't receiving an ignition pulse. It certainly seems likely that you could bypass the whole mechanism and get the ECU to fire up the fuel injectors if you could get an ignition pulse. The ECU doesn't handle spark control as the early turbo systems used vacuum advance so you could just install a non-turbo EA81 distributor and assuming you have power to the coil you should get spark and an ignition pulse signal from the coil negative. That should get the ECU to fire off the injectors if it is otherwise functional.

 

Have you checked the ignition relay under the passenger seat as I mentioned previously? It powers all this stuff....

 

And does the fuel pump run when you are cranking the starter? It should only run when cranking or seeing an ignition pulse. So if the fuel pump runs when cranking, then the ECU is turning on the fuel pump relay as it should and is likely functional but not fireing the injectors because it isn't seeing an ignition pulse. If nothing has power including the fuel pump then you have a power supply issue - something like the ignition relay under the seat.

 

GD

[naru]

 

I worked on the BRAT today but still have not been able to solve the "no start" problem. I am curious what you may think about the Ignition Control Unit? I am not familiar with any test for this item except for installing a known operable unit. The problem is that I have not been able to locate a replacement unit to purchase. The reason is that there was a special Hitachi Distributor and ICU plus an ECM and harness compatibalilty issue on cars originally sold in California (it has 4-wires on the ICU) and all of the ICUs or Modules that I have located are 2-wire ONLY and specifically NOT offered installation in California vehicles. Beides the California requirement, I do not know if a 2-wire unit would work anyway?

 

Gotta' go for now.

 

Thanks again for your comments.

 

Best wishes,

 

Don Cordier

Simi Valley, California USA

TEL: 818-400-2848

 

You certainly don`t need an ECM/ECU.

No ignition pulses = no injector pulses.

ECU is Calif. specific,4 wire ICU is not.

 

Best ICU test is to look for an intermittent ground connection at the coil negative terminal w/the module powered up and dizzy turning.

Multimeter diode check function will usually show an open or shorted circuit between some of the 4 terminals of a bad one.

 

Make sure you have 12 V on coil negative.

[DonCordier]

Hi Rick,

 

I wanted to attach an image of the ICU (aka the "ICM" - Ignition control Module - as most parts stores use this designation for the descriptive term) but I do not see any way to accomplish the attachment???

 

Regarding the ignition relay - no, I completely forgot to check this ignition relay (did not put on my checklist!!!) but will do that this weekend.

 

Regarding fuel pump operation - I am not certain that the fuel pump is operating when the engine is cranked (I thought it was but...). I will get an assistant and re-check this point too when I re-test everything this weekend.

 

I am going back to the drawing board and re-checking every circuit, connection, relay, etc. this weekend. Sometimes these problems can be downright frustrating.

 

Again, thanks for your follow-up, research and suggestions.

 

Best wishes,

 

Don Cordier

Simi Valley, California USA

TEL: 818-400-2848

 

Looking over my wireing diagrams I think the component you are refering to is the ICU for the knock control unit. The ICU interfaces with the knock control unit to allow control over high-altitude spark advance. Above 1400 feet elevation it advances the timing by 5 degrees apparently.

 

It is seperate from the ECU though, so I wouldn't think the operation of it would affect your fuel delivery unless the ECU wasn't receiving an ignition pulse. It certainly seems likely that you could bypass the whole mechanism and get the ECU to fire up the fuel injectors if you could get an ignition pulse. The ECU doesn't handle spark control as the early turbo systems used vacuum advance so you could just install a non-turbo EA81 distributor and assuming you have power to the coil you should get spark and an ignition pulse signal from the coil negative. That should get the ECU to fire off the injectors if it is otherwise functional.

 

Have you checked the ignition relay under the passenger seat as I mentioned previously? It powers all this stuff....

 

And does the fuel pump run when you are cranking the starter? It should only run when cranking or seeing an ignition pulse. So if the fuel pump runs when cranking, then the ECU is turning on the fuel pump relay as it should and is likely functional but not fireing the injectors because it isn't seeing an ignition pulse. If nothing has power including the fuel pump then you have a power supply issue - something like the ignition relay under the seat.

 

GD

[naru]

Strange as it sounds,the ignition relay has nothing to do w/the ignition system.

If the tach shows 0 rpm while cranking,you need to troubleshoot the ignition primary circuit.

[Gloyale]

Hook a test light to the negative side of the coil while cranking. Watch tho see if it pulses

[DonCordier]

To Both "naru" and "Gloyale",

 

Thanks for your input. Both suggestions are interesting and will be very helpful tomorrow when I resume my troubleshooting exercise.

 

BTW - Does anyone know of a good Subaru shop in the Simi Valley/West San Fernando Valley area? I may have to resort to the "Paramedics"!

 

Have a great weekend...

 

Best wishes,

 

Don Cordier

Simi Valley, California USA

TEL: 818-400-2848

[s'ko]

Don.

 

you might want to take a look at this thread

 

http://www.ultimatesubaru.org/forum/showthread.php?t=79249

 

It ended up being the distry module.

 

He ended up selling the BRAT, but it ran when Shawn sent him a new module

 

later

 

BW

[lrgvanman]

 

Edited July 4, 2020 by lrgvanman
Delete

[lrgvanman]

Going through similar problems with a 1984 GL wagon. I tried to open that thread but it only comes up blank. I changed distributor while suspecting ICM. Car started and ran until I shut it off 20 minutes later. I tried to restart this morning to finalize with a timing light and idle adjustment but won't start now like before the dist change. 

[lrgvanman]

Coil put out weakly and failed internal resistance but installing brand new coil does nothing. Same results. Very weak pulsing spark and both terminals of the ICM stay hot. Looking for way to diagnose ICM resistance. Probably just going to replace with my new spare ICM and see if that solves it.

[oczuk32]

Reviving this post cause my wagon is starting with the same issue.

Has anyone come up with a solution or the cause?

Currently, I unplug the and plug the wire harness to get the ECU to work. Then when it sits for a while like the next day. The wagon won't start until unplugged and plug the harness to the ECU.