NO ECM Data

[Guest sehrhardt2]

Hello fellow reatta owners,i was wondering if you would be able to help me out with some issues with my 89 Reatta.

Some of the many issues include

1.) Computer communication problem detected

2.) electric problem light is on

3.) When you go into the ecm option in the diagnostic center is says "No Ecm Data"

4.) code b334 is current

5.) car only starts when fuel is poured or sprayed into intake manifold and when it does start it doesn't idle and it dies quickly

6.) Low oil pressure message is showing up

Any help or suggestion is greatly appreciated

Edited April 26, 2014 by sehrhardt2 (see edit history)

[Ronnie]

Welcome to the forum. Sounds like you have a fuel pressure problem preventing the engine from starting. Instructions for testing the fuel pump can be found here: Fuel Pressure Testing If you want to try a simple test connect 12 volts to the fuel pump prime/test connector as shown in the photo below. The fuel pump should start running as soon as you connect 12 volts to it.

Click to enlarge image

I don't think the code B334 will keep the engine from starting. I would get it running and then work on the other problems.

[Guest sehrhardt2]

fuel pump is working fine and pressure read 41 psi when i checked it earlier today while working on the car any other suggestions. also when i was working on the car today i refered to the engine cranks but wont start of the the repiar manual and when it said to put the test light in the fuel injector connect and turn the key to the on position the light was on steady. i know the manual says to look for i open ground but i have no idea what that means. could someone please explainto me what that means and what i would need to do to fix it

[Ronnie]

One wire going to the injector is hot any time the key is in the run position. The injector opens momentarily when the ECM grounds the other wire going to the injector. Perhaps the service manual is telling you to check the ground circuits? You really need a "noid" light to test the injectors properly.

[Ronnie]

I would check to make sure you have good battery voltage and clean and tighten all the grounds. Ground Terminals & Junction Box Location If all is good you might have a bad ECM.

[Guest sehrhardt2]

all grounds were cleaned recently and the ecm was replaced within the past month

i will go out at some point to get a noid light

some of the other work ive done recently include a new crank position sensor , new harmonic balancer, new coil pack, new camshaft sensor, new fuel line filter, and a fuel pump relay.

[TexasJohn55]

Check and re-check ALL fuses, they may be in multiple locations, I'm not sure on that car.

Injectors click when they fire, you can use a screwdriver and put the butt end to your ear while touching the injector. Noid lights are good though.

No comm with the ECM is BAD......Do you have a troubleshooting tree for that? Maybe one wire connection shutting it down. Be sure all connectors are seated properly especially at the computers. You might try unplugging and inspecting the pins and females and re-connecting everything.

Will it communicate with a scanner at the on board OBD datalink connector, if it won't the computer is not powered up.

[Ronnie]

fuel pump is working fine and pressure read 41 psi when i checked it earlier today while working on the car any other suggestions

When you checked fuel pressure did the fuel pump run just by turning the key to the "run" position OR did you have to spin the engine with the starter before you got fuel pressure? If the pump will run for a few seconds each time you turn the key to the run position the ECM is powering on. However, the fuel pump will still run if the engine spins enough to build oil pressure, even if the ECM is dead.

Since the engine will run by pouring gas into it I think you can rule out the ignition system including the crank sensor, ICM and coils.

[Guest Mc_Reatta]

Check battery is at least 11 volts.

Pull cover off passenger's side of center console to get at the interior relay center.

Check fuse 5 on it (IGN/ECM).

Disconnect and reconnect the three connectors to the ECM.

[KDirk]

I would suggest that the ECM is the central issue here (at least until it is back on the line communcating with the other modules. While the ECM has a limp home mode in the event of a MEM-CAL failure, complete loss of the ECM will generally leave the car in a no-start/no-run conditon.

The fact that the ECM is not on the bus means either a hard-failed ECM or that the network is broken on both sides of the ECM. Think of the network as a loop, with two connections at each module, one from either direction. One can be lost and still maintain communication but if both are lost the module is isolated with no connection to the rest of the network.

Verify power to the ECM first of course. Checking the integrity of the loop is easy enough with a continuity tester. Disconnect the plugs from the adjoining modules and the ECM and test from the ECM connector to the adjoining modules connector on circuit 800 (tan wire). This will verify the loop is intact both up and downline fom the ECM. If not, wiring or connector issues need to be addressed first.

If the requisite power supply circuits are working and the network loop checks out, then it is almost certainly a bad ECM. I did forget to mention to verify good ground to the ECM as well. A bad ECM will frequently have visibly damaged (burned/discolored) components on the circuit board if you remove the aluminum upper cover to inspect it.

If the ECM is bad, you'll need to swap the MEM-CAL (PROM in non-GM speak) to a replacement unit. After the ECM failure has been recitified, any other problems can be addressed in turn. I would concentrate on the ECM first however, as it may be the principal underlying cause of your problems.

KDirk

[Guest sehrhardt2]

Thanks for the suggestions, are there any specific wires i should check going into the ecm to see if the ecm is getting powered. and are their any specific wires going from the ecm to to the a joining modules i should check thanks

[Guest sehrhardt2]

also does any one have the ecm wiring diagrams as well as the bcm wiring diagrams so i would be able to see how the ecm get power as well as how the ecm connects to the bcm. Page numbers for these wiring diagrams for a 89 service manual would also be greatly appreciated

[Guest Mc_Reatta]

ECM wiring diagrams start on page 6E3-A-3 of the 89 FSM and repeated starting on page 8D1-7.

BCM pinouts are on page BD2-2

Edited April 26, 2014 by Mc_Reatta (see edit history)

[Ronnie]

You can check to see if the ECM is getting power by connecting a volt meter to the green fuel pump test connector and turn the key to the run position. Don't try to start the engine.

If you see 12 volts for a few seconds each time you turn the key from off to run the ECM is powered up and activating the fuel pump relay as it should. If the ECM has power check the main ground point for the ECM to make sure it is clean and tight. I believe it grounds on a stud on the intake or the cylinder head on the passenger side. Mc_Reatta might have a photo that would show the location.

Edited April 26, 2014 by Ronnie (see edit history)

[KDirk]

Very good advice from Ronnie, the green fuel pump prime connector under the hood is a much easier way to check for power to the ECM than the alternative of backprobing the ECM connector. The data line continuity still would need to be tested at the respective module connectors.

KDirk

[Guest sehrhardt2]

Just to put this out there i bought a used prom from a junkyard due the the fact that when i replaced the ecm the original prom got lost somehow. Is there a way to tell if it is the correct prom for my 89 reatta

[Guest Mc_Reatta]

Post the PN and 4 letter code and someone can look it up. This may have a lot to do with your problems.

[KDirk]

Hoh boy. The dreaded PROM mismatch. Do you know what car the replacement ECM and PROM came from? Also, what year is important. 88 vs. 89 PROMS are usually different even for the same model of car with a 3800 engine. I found this out when I bought an 88 coupe that someone had previously installed an 89 Reatta PROM in. Caused all kinds of problems in addition to having a bad ECM.

You are going to need the correct PROM and a known good ECM before you do anything else. Otherwise, you will be chasing your tail trying to figure out what is going on.

KDirk

[Guest sehrhardt2]

No idea what car or what year the prom came from, but the ecm was bought from the local napa refurbished. Do you know were i could order the correct prom from?

Edited April 27, 2014 by sehrhardt2 (see edit history)

[KDirk]

Hopefully Padgett will see this and chime in as I don't know the correct code for an 89 Reatta ECM PROM. I know 1988 is ANCX, which was the final revision for federal emissions version. Each year is unique as is each model, even if running the same engine and transmission combo.

So, a 1988 Reatta is different from a 1989, and an Olds Toronado (just for example) is a different PROM from a Reatta of the same year despite both being E platform cars with a 3800 engine.

Look at the PROM you have. Through an opening in the blue plastic cover there will be a silver sticker with black printing visible. This will show a four letter code. Post that here and hopefully we can cross reference it to see if it is the correct one (or not).

If you have the wrong one, getting a proper replacement will not be so easy as GM no longer offers these as replacement parts. Either it will have to come from a donor car of the correct year and model or you will need to find someone who can modify a MEM-CAL with the correct PROM image for your car.

Some tuners may be able to do this if they have the correct original ROM saved as a file. A new PROM can then be burned and installed in the MEM-CAL so it will work in your car. I have the device to program one, but do not have an 89 Reatta ROM image to burn a new chip from, otherwise I'd offer to put one together. All the files I have are for 88 models as I own two of them, but no 89's.

KDirk

[Guest sehrhardt2]

The prom currently in the ecm says

Delco

AJRZ

9244

Does anyone know if this is the correct prom for a 89 Reatta?

[Guest Mc_Reatta]

The prom currently in the ecm says

Delco

AJRZ

9244

Does anyone know if this is the correct prom for a 89 Reatta?

It is not the correct PROM.

89s used the ANNH, APTN, and ASSU

Believe ASSU (PN 16141300) was the latest one.

Will display 1094 when ED99 is called for.

Edited April 27, 2014 by Mc_Reatta (see edit history)

[Ronnie]

I think you probably have found your problem. That prom doesn't appear to be for a Reatta of any year.

[Guest sehrhardt2]

Does anyone know were i could find the correct prom? Preferebly the most updated one.

Could someone also give me the numbers for the ecm?

Edited April 27, 2014 by sehrhardt2 (see edit history)

[Guest Mc_Reatta]

If you can find an ECM out of an running 89 Reatta with EPROM, that would be your best bet.

PN for the ECM is 1228253 (probably what you have now).

GM Parts Direct is about the only place you can find a EPROM new. They show it listed but would have to confirm they have it in stock.

Edited April 27, 2014 by Mc_Reatta (see edit history)

[DAVES89]

This is getting interesting.

In my backstock I have the following;

ECM #16198264

ECM #1228253

E Prom #APTN

E Prom #ASSW

E Pron #ASSU

Mc_Reatta did you transpose your ECM #?

On my #16198264 ECM it is marked "Remanufactured Original Equipment". What do I have here?

Edited April 27, 2014 by DAVES89 (see edit history)

[KDirk]

Dave,

As an aside, when I get up there (eventually) I'd like to copy the contents of those PROMs (can be done non-destructively) so I can build a library of ROM images for future use. Hopefully you will still have them when I make my visit.

KDirk

[Ronnie]

Here is a list proms if anyone wants to search through them. It tells the ECM numbers and other data about them. Prom Lookup

[Guest Mc_Reatta]

Mc_Reatta did you transpose your ECM #?

Yes Sir I did. Good catch. I will edit that post for posterity.

[Guest sehrhardt2]

Thanks for the help everyone. I will order a new prom from GM Parts Direct as soon as possible, and i will get back to you all with what happends when i install the new prom

[Guest Mc_Reatta]

GM had reliability issues with the original ECMs, PN#1228253 and improved the design and when remanufacturing defective or unused units and installing the improvements, changed the PN to 16198264.

So the 16198264 is the preferred one to get for use as a replacement. Don't think it was ever issued as a "new" part for factory cars, only as a reman product. Seems to date to about 1990, so what's in any specific car is a crap shoot.

[Guest Mc_Reatta]

E Prom #APTN

E Prom #ASSW

E Pron #ASSU

APTN was the PROM in the first production 89s

It was replaced about 2 months later with an upgraded one.

ASSU (16141300) was put into the Fed model cars, ASSW (16141305) was put into the "left coast" California model cars.

So, if you live in a state that still smog tests your Reatta you may want to go with the ASSW.

[Guest sehrhardt2]

So since i live in Ct i should probably get a ASSW prom.

Somebody please correct me if im wrong. Also if I order a prom from GM parts direct which prom would they sene me or would they just grab a random one that works for a 89 reatta

[DAVES89]

I Have an ASSW prom...

[wws944]

It would be interesting to know the difference between the Federal and California PROMs. For the record, my Federal car has no problems passing California smog tests though.

[Guest Mc_Reatta]

GMPD should supply the specific PN you order which will control what program version you get.

In 89 CA specified new cars have reduced hydrocarbons and nitrogen oxides emissions compared to US standards. So if CT measures for these as part of its smog testing you might benefit somewhat from the CA PROM.

Most states don't test older / high mileage cars anymore since they can't meet tough standards they weren't designed for, deteriorate with age, and don't make up a large percentage of cars on the road to make them worth going after.

Don't know how tough CT testing is, but seems most CA owners can still pass their tests without too much trouble.

[Guest Mc_Reatta]

Difference between 89 Federal and CA emission standards were:

.............................FED........CA

HC grams/mile..........0.41......0.39

NO grams/mile..........1.0....... 0.82

Maybe KDirk can determine what tweaks were made in the ECM program to help Buick meet these slight changes after he gets to compare the two PROM versions.

Edited April 28, 2014 by Mc_Reatta (see edit history)

[KDirk]

I would need to dump both PROMS and do bit-level analysis to figure that out. Dumping the code on the roms is easy (with the requisite hardware) but doing the analysis is time consuming and difficult.

All one has to look at are strings of raw data in both hex and ascii (with the utility I use anyway) so there is much guesswork concerning the significance of any particular part of the program code until one has mapped out the program structure.

If I can get the proms long enough to copy them to disk, I can not only make new PROMS if needed, but could try to analyze the difference for Fed vs. CA versions.

At this point, the only PROMS I've imaged are the 1988 ANCX (final federal revision) ECM ROM and the 1988 and 1989 CRTC PROMS. I do not have access to an 89 vehicle to pull the MEM-CAL and copy its contents.

KDirk

[DAVES89]

Kevin, You saw my list. Tell me what you want...

[KDirk]

Dave,

ASSU and ASSW for sure since these were the final production PROMS for 89. I don't see much point to copying APTN since it was superseded. That said, the effort to copy is minimal and perhaps would be good to have an archival copy. These require very little storage space (32kbytes per ROM) so it is nothing to store even the superflous ones.

I have the concern that new PROMs are generally not available from GM SPO any longer, since anything of our vehicles vintage is long since considered obsolete. I know there were no new 88 PROMs to be had when I had all the trouble with my first 88 a few years back. I had to roll my own, though Padgett was gracious enough to provide me with the ROM image to burn into a new chip. Without that, I'd have been forced to find a good ANCX PROM from a donor car.

My eventual intent is to have a library of all pertinent PROMs stored to bail out owners who find themselves needing one that is not readily available. Hoping to get the 91 ROMs copied while working on the convertible here soon.

It would be great if one or more of the go-to sites (ROJ, reatta.net, etc.) could host these files at some point so they are readily available to all Reatta owners. I don't know if some stuffed shirt at GM would object to that, however. I do realize not many people own a PROM burner but if you have at least the file, you are halfway there and could find a tuner shop to make the chip if nothing else.

If you end up needing to sell the ASSW unit, then we will need to track down another for me to copy, or figure out some other arrangement. If you have them all still when I make my visit, I'll bring the computer and burner with me and copy them at your place rather than having you send them down and have to ship them back.

KDirk