I think I?m in deep 💩

[JT_n_CT_90_ZR1]

So I finally pinpointed why my car is going bananas. I have called three different computer shops and each said they can?t fix my BCM.
I took my BCM apart and one of my DELCO 60904 chips is fried. It didn?t ruin the board but it needs to be replaced. It falls in U4 circuit. Does ANYONE know of anyone that has experience fixing this? 1990 ZR1 Vats 15- (anyone know of one for sale?) lastly does anyone know if I can buy a ?90/?91 BCM and use it as a parts donor?

https://imgur.com/a/gw64DJp

[JT_n_CT_90_ZR1]

http://imgur.com/a/gw64DJphttp://imgur.com/a/gw64DJp[/IMG]

[dredgeguy]

Just saw this group listed in another post, looks promising? Keep us all posted and good luck.
https://www.zr1ecm.com/wefix.html

[-=Jeff=-]

So I finally pinpointed why my car is going bananas. I have called three different computer shops and each said they can?t fix my BCM.
I took my BCM apart and one of my DELCO 60904 chips is fried. It didn?t ruin the board but it needs to be replaced. It falls in U4 circuit. Does ANYONE know of anyone that has experience fixing this? 1990 ZR1 Vats 15- (anyone know of one for sale?) lastly does anyone know if I can buy a ?90/?91 BCM and use it as a parts donor?

https://imgur.com/a/gw64DJp


I can program a BCM for you.. Get one off of eBay and I can program all the specifics, I have done over a dozen so far and currently have one in my 1990 (from a 1991)


If you do a 1991 BCM in your 1990, the LCD will be brighter like the 91-95 and easier to be seen in day time. PM me for details and cost

[JT_n_CT_90_ZR1]

Thanks man. I appreciate that. I have the Tech 1 does that program them also? Curious. (Admittedly never used it, just grabbed it because they are rare) in any event, I will 100% buy one asap. Pm me to exchange info?

[-=Jeff=-]

Tech 1 can only program one that has not been previously programmed and you also need a specific cartridge for programming.

I can reprogram units that have been previously programmed. I will send a PM later today

[JT_n_CT_90_ZR1]

@jeff can you email me. I can?t figure out how to reply to the PM. 🥴😂

Leoct81@icloud.com

[phrogs]

I have a 90 and 91 BCM 90 is a code 10 vats the other I am not sure.

[JT_n_CT_90_ZR1]

I have a 90 and 91 BCM 90 is a code 10 vats the other I am not sure.

I just ordered one off of EBay and I?m shipping it to Jeff to program for me. Thank you however.

[JT_n_CT_90_ZR1]

UPDATE: JEFF reprogrammed a ECM I ordered online and sent both to him. The one he programmed works fantastic! Everything is communicating ETC. Recommend his services.

On that note, we are running down the list here. Still no crank, I am ordering an ignition switch as we speak and new battery cables just in case. Any other Ideas? And yes it?s a Brand new oversized 1000 CCA battery. vatts? Advice?

[Starman]

Try pulling the CTSY fuse, top left to reset VATS.


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[XfireZ51]

Jeff, does ur reprogramming also allow changing the black on orange to white on black for the LCD display?

[-=Jeff=-]

Jeff, does ur reprogramming also allow changing the black on orange to white on black for the LCD display?


not for that you need the reverse polarized kit from Batee, then you need a white backing to swap from the orange


EDIT..

you would need this:
https://batee.com/collections/1990-1996-corvette-parts/products/1990-96-color-invert-kit-for-lcd


and like this but not orange
https://batee.com/collections/1990-1996-corvette-parts/products/1990-1996-corvette-cluster-lcd-color-filter?variant=42570426843291

[HAWAIIZR-1]

Wow Jeff! You are da man and good to know this. What can?t you do? Awesome.


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[XfireZ51]

not for that you need the reverse polarized kit from Batee, then you need a white backing to swap from the orange


EDIT..

you would need this:
https://batee.com/collections/1990-1996-corvette-parts/products/1990-96-color-invert-kit-for-lcd


and like this but not orange
https://batee.com/collections/1990-1996-corvette-parts/products/1990-1996-corvette-cluster-lcd-color-filter?variant=42570426843291

Seems like they?re out of stock on the LCD filter. Let?s chat pizza night.

[rush91]

UPDATE: JEFF reprogrammed a ECM I ordered online and sent both to him. The one he programmed works fantastic! Everything is communicating ETC. Recommend his services.

On that note, we are running down the list here. Still no crank, I am ordering an ignition switch as we speak and new battery cables just in case. Any other Ideas? And yes it?s a Brand new oversized 1000 CCA battery. vatts? Advice?

Is the car cranking or do you turn the key and nothing? If it's cranking but won't start it could be your fuel pumps......

When you turn the ignition on BUT don't start the car, you should hear the pumps in the tank priming.

[JT_n_CT_90_ZR1]

I was thinking that also. However I did just replace the BCM and for what I?ve been reading I have to get the ECM and BCM to communicate which unfortunately are not. I am getting ERR when jump 1&2. So in a nutshell, I think I have a short with the communication wires. I have a feeling I?m going to have to take the whole dash off to find this short or at the very least why it?s not communicating.
Jeff did a fantastic job reprogramming my BCM and my ECM is brand new with my original EPROM.
As we speak I have the ABS module and that section in the back apart seeing if there is anything wrong with the wiring or modules.
There is something electrically wrong because my old BCM had chips completely burnt up. Several of them.
I have a 1966 427 I have that needs some love too so I am just trying to get the 90 Z in at least drivable condition just in case I need to bring her somewhere for another set of eyes to checkout. Unfortunately I am just a normal guy with a normal paycheck so whatever I can do myself is key.

[RSLyrick]

Hey,

what makes you think that the ECM and CCM password exchange routine fails ?

If the FEDS is failing (Fuel Enable System), so this password exchange between the modules, you should get a DTC 54. Security lamp and SYS will also flash. Is this the case ? DTC 41 may be set as well .

If this safe communication fails, the fuel pumps are normally still getting primed but you will get no fuel injection so no start. Do you hear them running after ignition ?

Refer to 8D-62 for more details (about DTC 54) and 8D-54 (about DTC 41)

Do all the DIC classic bulbs light up after ignition before cranking ? (especially the SES light)

If you want to check the communication wires (UART), no need to dismantle the whole dash at the moment.

- Battery connected : check with a multimeter if you get 5V in the DLC (diagnostic) port at pin M, with ignition ON.

To check the second UART wire, same procedure, it could be probed at the back of the ECM (D15 and D20), same expected voltage value around 5V with key in ignition position.

That should help you check if you have a short to GND or 12V or something else.

For an open wire issue, it would be better to disconnect the battery, the ECM harness and CCM harness as well and do a continuity test with your multimeter between the ECM harness and CCM harness connectors.

You have to do this because two other modules (ABS, C68) are connected on this bus and they have all have (possibly) the capability to pull it to 5V, so you need to isolate the connection to these modules.

[JT_n_CT_90_ZR1]

Brother that is some fantastic advice. And Yes, I have every single warning light Except the Check engine.

Next, when I turn the key to on, I have the vacuum pump intermittently buzzing and the fans go on I can?t hear the pumps but before this happened I had no problem with them so I don?t think they are an issue but they are cheap so I should just order a couple for the shelf. I did just order an ignition switch, waiting on that also. Security and system lights flash and the security light eventually goes off like normal which I was told is good because the Vats accepted the key. I do see a flashing SRS light that seems to be flashing a code I just don?t know how to read it accurately. For example- I count the flashes but how do I know when it?s finished with a specific code?

Lastly, I know you are all going to scream at me for this, but I don?t have a 1990 Service book set yet. I just keep putting it off and try to look up everything online.

I do have the factory LT5 service book. I also have a file with the full factory 1994 C4 dual book jailbroke so it?s transferable. I found it randomly online and scanned it for virus? and it?s safe (if anyone needs please shoot me over your email) and I have a digital 1990 C4 usb-drive also that is more for parts then troubleshooting.

I?ll get the voltage numbers over tomorrow. I have a feeling they are all working correctly as from what you described should be working is. If in fact, it is the FEDS what is the procedure on fixing or replacing that? I have poor pressure in the rails and it just drips out when in check the valve on the end of the passenger side fuel rail.

We are going back to Spring but the last time I drove the car the secondaries were not activating and the Check Engine light was sending me O2 sensor codes. (Both were replaced) and then my BCM started going bananas and the poltergeist started making random things happen which are now perfect with the new BCM Jeff reprogrammed.

[RSLyrick]

The SES / Check Engine bulb should light up briefly when you turn your key to ignition position. This is a good indication that the ECM is live and capable of controlling this bulb. Please double check (it is really fast).

If the Security light goes off, it means that the system recognized your key and FEDS was sucessfull as well (otherwise you would see SYS and SECURITY flashing together).

The secondaries vacuum pump buzzing is normal. The radiator fans have no reasons to start if the engine is cold. Are you maybe talking about the AC / blower running ? Try turning it off immediately after turning the key to get the environnement as quiet as possible.

To do the test in a quiet environnement. If your secondaries vacuum pump has a leak, it may run almost continuously, making too much noise for you to focus on the sound of the fuel pumps.

If the fuel pumps are running, that's another indication that your ECM is alive.


To get some diagnotic code out, short pin A and B from the DLC connector.

The CCM will display Err when attempting to display ECM DTCs for the LT5 engine.

You will readout codes by counting the amount of time the SES light is flashing.

Once you have grounded the diagnostic pin (A to B), turn the key to ignition.

Look at the SES light. It will start with a code 12 indicating that the diagnostic system works properly:

- 1 flash / waiting time / 2 flashes

This will happen 3 times.

Then stored codes will also be shown to you in the very same way (exemple DTC 32)

- 3 flashes / waiting time / 2 flashes

This will happen 3 times for a specific code, longue pause before repetition, then moving to the next stored code if any

For the diagnostic code of the CCM, litterally from the book.

To display CCM DTCs, select the Display DTCs mode by pressing the TRIP/ODO button until 1.1 appears in the trip monitor area of the cluster. Then, press the ENG/MET button to display the first DTC. Continue pressing the ENG/MET button to display
additional CCM DTCs, until the End-Of-Information indicator (---) is displayed in the speedometer. A C12 indicates no stored DTCs for the CCM. If it is necessary to go backward in the list, use the "FUEL INFO? button. The top of the DTC list will be
indicated by the --- display in the speedometer.

Yes, I will personnaly scream, get the books ! Second best investement in your life after the ZR-1 ! Lots of details and explanation about how your car actually works and how to investigate issues. I got the printed ones from Rockauto (DETROIT IRON editions), very good. And the digital version from another website, because it's much easier to look for info with the quick search function of a PDF reader. I sometimes read litterally like a standard book cause there so many interesting infos in it. Not like today's car repair book...

And check this fuel rail leakage at valve...not a good idea to attempt to start the car if you clearly see that there is a problem there. It will either run poorly, stall and it will completly hide the electrical issues that you may have

Also, Is the engine cranking ? Is the starter doing its job ? If you have a faulty starter, you may just hear a "click click" noise with no crank at all, or simply...nothing at all.

[JT_n_CT_90_ZR1]

First and foremost thank you for all this information. It?s amazing.

So when I start the car the engine fans go on, and and the vacuum pump goes on. No clicks, no start, no pumps. In the interior however everything comes on EXCEPT the Check Engine light.

[-=Jeff=-]

I forgot if you had the ECM looked at or tested. Make sure it is the correct ECM, also make sure the MEMCAL is secure in the ECM. With key on in a normal situation the fans will not come on, if you have the ALDL jumper for codes the fans will come on

[tpepmeie]

First and foremost thank you for all this information. It?s amazing.



So when I start the car the engine fans go on, and and the vacuum pump goes on. No clicks, no start, no pumps. In the interior however everything comes on EXCEPT the Check Engine light.



Sounds a lot like a mem-cal error. Either wrong mem-cal, not seated or damaged pin. The immediate cooling fans and ERR on the digital readout also are indicative. Didn?t read entire thread recently but have you tried a replacement known good ECM?



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[RSLyrick]

I didn't remember that the fan would start when A and B are shorted :) Good to know. Then, the question for JT_n_CT_90_ZR1 is, are the fans also starting when A and B are not shorted, ignition ON ?

I think the display is showing Err in the two following scenarios :

1) A and B jumped (ECM diagnostic) :

The CCM will display Err when attempting to display ECM DTCs for the LT5 engine. CCM display and clearing of ECM DTCs is available only for the LT1. Use the Tech 1 for ECM DTCs on the LT5.

2) A and G jumped (CCM diagnostic) :

If there is a communications problem between the ECM or EBTCM and, the CCM, the speedometer will display Err when the CCM is trying to communicate with the ECM or EBTCM.

Question for JT_n_CT_90_ZR1, do you also see Err when you do not short any diagnostic pin ?

Try to retrieve any CCM and ECM codes with the procedure which I described before.

I agree with Jeff and Todd, let us know if any kind of work has been done on your ECM :

- Repair job (also if you see a kind of seal / label which states that is has been remanufactured at some point)

- Calibration Chip installation (if you don't know, maybe you could open the ECM mem-cal door and take a picture of the currently used chip). As Todd mentionned, double check that is properly seated and that the connector is not bent.

- Anything that you may have done that could have caused damages to the ECM (removal, jump start, battery polarity inversion...). I know a guy who did accidently a reverse polarity connections on his LT1, so far all the car ECUs (ECM, CCM, ABS...) were functional so I doubt that it would have caused damaged to yours if you did it, but still, let us know.

Opening the ECM to look for damages is a bit more tricky procedure than for your CCM but feasible if you are familiar with handling fragile stuff...but try to retrieve diagnostic codes for the CCM and ECM first. This can really help.

If damages happened on your CCM, similar damaged may have happened on your ECM as well. Either caused by anything that you may have done or the CCM failure itself led to the ECM failure due to their shared interfaces (UART). I have seen this in other cars ECUs where interfaces were poorly protected, one failed leading to damages to the other one...

So, you got no fuel pumps running and no check engine light when ignition is ON without diagnostic enabled. This sounds like an ECM issue but too early to confirm.


No crank : starter toasted or starter relay not triggered by the CCM (security issue then or something else)


Get us some DTCs if any ! :cheers: