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Re: Hacking into the 86-88 Trans Am digital dash odometer
BizJet,
I have an 89 Formula that I am gathering the DD swap for. I only need harnesses. I have yet to touch the car though and would consider a complete swap dash and all harnesses with you. I would like to have spares of the DD boards. Do you have digital HVAC too? I do need all that.
Dude I just saw that I am only 45 min from you in Boynton. We need to talk!
Re: Hacking into the 86-88 Trans Am digital dash odometer
Originally Posted by TallTim
BizJet,
I have an 89 Formula that I am gathering the DD swap for. I only need harnesses. I have yet to touch the car though and would consider a complete swap dash and all harnesses with you. I would like to have spares of the DD boards. Do you have digital HVAC too? I do need all that.
Dude I just saw that I am only 45 min from you in Boynton. We need to talk!
Cheers, Tim
TallTim - I just picked up a 1989 Formula 350 - so i think I am going to be selling the GTA - let me think about it a couple days and I will let you know.
We should meet up at Cars & Coffee in WPB sometime - Thanks
Re: Hacking into the 86-88 Trans Am digital dash odometer
Originally Posted by BizJetTech
TallTim - I just picked up a 1989 Formula 350 - so i think I am going to be selling the GTA - let me think about it a couple days and I will let you know.
We should meet up at Cars & Coffee in WPB sometime - Thanks
Please show some pictures of the Formula! Did you find it locally? I searched for a year and found mine in DC 1K away from me. Of course in S FL everything is at least 1K away....
Re: Hacking into the 86-88 Trans Am digital dash odometer
As I go through this thread again. I really wish I had a easy test set/code loader that I could just attach to my laptop via usb. I have no idea how I would load these files onto the chips.
Re: Hacking into the 86-88 Trans Am digital dash odometer
Originally Posted by Cehbra
As it looks there are not many more secrets left, the biggest one being the threshold on when that last digit before the comma changes from 0 to 5. I might tackle that some time. For now I hope that new information is of use to someone.
Cheers!
BRAVO. You certainly have helped a lot of people out who can understand all this. I believe we could possibly have made a woman out of a barbie bv back in the 80s! Obviously, I would have brought the Barbie & you would have done the rest....
GREAT WORK!!!!
Now to be able to apply it.
Re: Hacking into the 86-88 Trans Am digital dash odometer
Hi everyone, great tread. I know the last tread was long time ago. But I need help with my odometer board. I need to know what is this part and if it's possible to replace a broken one for a new one.
I identify it on a previous picture posted here, at the beginning. Sorry for that.
Re: Hacking into the 86-88 Trans Am digital dash odometer
Just google the numbers on it listing a transistor. Or go to a electronics store. ..computer repair and such. Mouser, Digikey, any of them, Radio Shack...
Re: Hacking into the 86-88 Trans Am digital dash odometer
Maybe my google skills are severely lacking but I spent half an hour searching for a 5 pin TO-220 package IC and came up empty. Can you take close up pictures of the board to see if we can make out what the purpose of that chip was and find an alternate part that way? The part was made by National Semiconductor.
Last edited by Jaime-TA-84; 12-19-2019 at 12:37 AM.
Re: Hacking into the 86-88 Trans Am digital dash odometer
This is great info! My odometer is currently flashing and hopefully this will help me resolve the issue. for some reason I cannot send a private message yet, didnt figure out the process. @Cehbra, do you have anymore chips for sale?
hello
I have problem with my odometer, it flashes 999999.9. Is that broken /fixable or what? Car dont have original ecu, but does this need it anyway? This car has been sleep past 16years because engine fire. And now it is rebuild almost ready, and can test with battery. There were missing few grounding what I put there. And now dash seems to be Ok, but this odometer… also those buttons wont do anything
Re: Hacking into the 86-88 Trans Am digital dash odometer
Originally Posted by Cehbra
No one interested in this topic?
In that case I'll just carry on with my digital dash project, I guess. Gonna post the progress in my build thread.
I am interested in this topic I have a 1984 trans am I'm going to be swapping in an 87 digital dash into and my car has 32k miles and this new dash i am putting in had around 167k miles. It would be nice to know how to change this dash to the right milage
Re: Hacking into the 86-88 Trans Am digital dash odometer
Originally Posted by Badbird33
I am interested in this topic I have a 1984 trans am I'm going to be swapping in an 87 digital dash into and my car has 32k miles and this new dash i am putting in had around 167k miles. It would be nice to know how to change this dash to the right milage
My computer didnt load the rest of the post and I just read it and wow there is so much useful information. Is there any way I can still buy one of the chips and have it programmed to save me the trouble? If not i would be fine sending the one I have in to be changed. Thanks
Re: Hacking into the 86-88 Trans Am digital dash odometer
Originally Posted by Cehbra
Well, that’s it! Now I’ll be moving on to getting the digital dash and some other interior stuff ready to go in the car! Excited, holidays may come!!!
One more thing: I had bought myself a handful of NOS NCR52801 chips for testing purposes, that I don’t need anymore. So if someone is interested I will gladly get rid of them one by one. To (barely) cover my expenses US$ 60 per programmed chip incl. shipping and handling should be a fair price. If someone has a chip and needs it programmed you can send it in as well. If interested, shoot me a pm.
Interested in a programmed chip, if still available.
Re: Hacking into the 86-88 Trans Am digital dash odometer
Good morning ,
I am writing this way because otherwise I cannot contact Cehbra. I read very carefully the wonderful "fight" with the digital counter and I have a similar problem. I have a 1990 Pontiac Grand Prix and I bought digital clocks for it. Everything is OK, but of course there is a problem with the mileage of the car. My original mileage is 153,000 km and the mileage on digital clocks is 220,000 km. Of course, there was a need to set this mileage to the correct value. However, there is another EPROM there. The symbol of this memory is 25072478 REV D. The housing is DIP 16. Is it possible that this is the same memory as in this case, as described by Cehbra?
Re: Hacking into the 86-88 Trans Am digital dash odometer
Dear readers
I've recently done two repairs of Trans Am clusters in Stockholm, Sweden.
Several problems have been addressed and finally found solutions for.
First customers main complain was that the E/m button would only switch between miles/ km on the odometer and would not transfer to the speedometer.
The second customers complain was that the cluster was unreliable, it would boot sometimes and sometimes not.
Reset signal was sorted and pulled low after replacement of the top right tantal on the odometer board
Stable supply voltage was achieved after replacement of the TO-220-5 transistor, we found that the LM2935 is a drop in replacement after lots of digging in 1986-ish data books.
(The TO-92 transistor above prom can be replaced with a standard NPN signal transistor 2N3904 will work just fine)
The switching signal from odometer to speedometer would work just fine and output high/ low signal while odometer board was by itself, when the speedometer was connected the signal would stay high all the time.
We create a small pcb with a Schmitt Trigger to boost the signal and this would solve the problem on the first cluster.
Happy about a working solution for the first cluster, we implemented the Schmitt Trigger board with no luck at all!
The signal would wiggle between 1.2-1.5 volt instead of 0-5 volt low/ high. We tried several methods to sort this issue: pull-up resistors, pull-down resistors, capacitor cleaners, nothing would help,
Next we tried a comparator circuit that would switch the outputs to 0/5v on a certain threshold value, hen connected the threshold value would move to another most likely due to the load changing.
The next tactic was to use the switch and trigger a new design circuit to output a high/low signal. we choose a flip-flop solution and with a Schmitt Trigger/ reset circuit to make the start signal low or high every time.
This made the circuit and cluster working 100%!
thanks for reading.
(the pictures are of the schmitt-trigger board on the speedometer board as well as the Switch board, please do reach put to us if you need any of the boards or repair help)
09-04-2018, 04:01 PM
