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'86 Turbo Z digital dash odometer memory chip question.( Not working)

7K views 40 replies 13 participants last post by  ILIKESHELBYS 
#1 ·
86 Turbo Z. The digital dash is fully functional except the digital Odometer reading. Reads blanks like this ---------- . From what I read, this has to do with the odometer memory chip??. In the 86 Turbo Z's , am I able to get another used chip to put in it? It really sucks though cause the car only has 63,000 miles on it. Now with the chip down, I cant even prove the car has low mileage. Any suggestions on what I can do ? How to see if it is in fact a memory chip issue.
Where is the chip located anyway ? lol
Any pics, tips, tricks would be deeply appreciated !!
Thanks
 
#3 ·
The odo info is stored on a IC chip, but I do not know which one. There had been discussion about this not too long ago, I think someone was trying to get ahold of a new one but the IC numbers were obselete. Sorry not to be much help!
 
#17 ·
Pulled the odometer chip out and placed it back in, wiggled lightly, etc... Still not working. This chip was sitting higher and closest to the window. Easy to pull out. Hopefully this was the right chip that was checked lol .

If this was the correct one...HOLY SMOKES !! It is ridiculously easy for someone to switch chips for a lower mileage one and flip the car for more money. I'm guessing that's why in '87 they started to change the easiness on changing these chips (from what I read on here)
 
#19 ·
No different or easier than swapping clusters, I have a 48k one original to the car, and a 208k that's in it. I don't ever plan to get rid of the car though.

Didn't mean to trash the thread, but yes, you pulled the right chip... something is telling me, there may be a protective feature on pulling and changing that chip, because when the dealer did it back in the day, there was an astrisk illuminated in from of the first digit of the odo readout. It's a bit of a mystery but DodgeG24Man has quite a bit of info on this stuff where he observed alot of it working for a Chrysler Dealer in the 80's
 
#20 ·
I don't even see where you trashed this thread lol . You didn't at all . Hmm, so if I get a diff. chip and put it in my car maybe it won't work. Let me read some threads by DodgeG24Man. It just might come down to finding a diff digital unit that works or somehow getting a unit repaired. Maybe somebody on here is handy at repairing these units. The mileage of 63k on my car that just got wiped out by chip did actually upset me . I wont lie. The thing is.. my engine is getting swamped out anyway soon so I shouldn't be too upset at this. I'm the type of guy that just wants every feature in my car to work. I hate starring at the stupid blanks where my mileage used to be lol . I love these cars !!!!
 
#21 ·
My 1984 had the dashes appear and after months of searching, found a chip, only to install it and right in front of my eyes go from mileage...back to the dashes. In my case, a short in the cluster, wiped out the chip. Make sure your cluster is problem free before putting in a chip so the same does not happen to you. As others have mentioned, it is easier to find a complete cluster than the chip. New replacement chips are not available to my knowledge. I know the company that made them, went out of business and Motorola bought one part of the company and the Chip, Electronics Section by a company in...Yeah we Know...China.
 
#22 ·
When I swapped my wife's cluster(84) for a better one it's mileage was just dashes. Swapped her chip into it and brought her mileage over to the new cluster. At the time I didn't know anything about this. I just saw the socketed chip, gave it a try and it worked. It didn't trigger an asterisk or any other sign that it wasn't stock.
 
#23 ·
When I worked in a Dodge dealer back in the '80's, and when we changed an electronic instrument cluster, we never swapped the chip. The remanufactured clusters started at zero with an asterisk to show that it was a replacement cluster. Then, in the box, there was a label that was affixed to the doorjam and we wrote in the mileage at the time of the change.
 
#25 ·
Hey Buddy !! So the whole thing about the asterisk popping up is all based on a re-manufactured digital dash cluster that was starting at 0 miles fresh? Did the asterisk ever disappear or did it stay there permanently to show it was a re-manufactured unit.
I see what you are saying. You write the actual mileage on the label and place it on the doorjamb . Then whatever miles you start to use on the new cluster gets added to the mileage on the door jamb. Makes sense. EX- 63k on doorjamb plus lets say you rack up 1k miles on the re-manufactured cluster = 64k actual miles . Got it ! Never new how they worked out the Math when it came to changing clusters :thumb:
 
#28 ·
That is the chip. I also researched and wrote the company before it was split up and sold. As you say, it needs to be programmed. There was someone on the board a few years back, Military/Electronic Engineer if I remember correctly that was working on the programing aspect but, have never seen any more of his posts. Since my dash shorted and ruined the replacement chip, sadly when I tried that chip on another cluster I bought, the mileage did not come back. So, junkyards and ultimately got 3 replacement clusters in working condition and have them as spares.
If anyone ever figures out how to program these chips and puts them up for sale,,, I would be interested in purchasing a couple of them.
 
#30 · (Edited)
I wish I could create one of the chips but No-Can-Do. I needed spares so went to junkyards and bought clusters. Found numerous of these during the Cash for Clunkers Program (what basically depleted our supply of 70's and 80's cars) and luckily found three good, working clusters and these are the ones I have for spares.

The one who was working on programming the chips was here on the forum a while back and said he had bought a lot of them on eBay and said he was close to getting the programming correct. I know other members told him they would buy the chip if he got it to work. It's been a while since I read his thread but it should not be hard to find. I did find the blank chips on a site but, they wanted over 100 dollars per chip. The Original Manufacturer of the Chip was General Instruments...hence the GI on the back of the chip.
I did find one of the threads that dealt with the chip http://www.turbododge.com/forums/f8/f35/351604-odometer-chip-id-requested.html
 
#34 · (Edited)
Hello everybody - I actually just found the time to resurrect my investigation. I had an old power up logic analyzer trace on the control and data lines on the ER1451 odometer ROM and just wrote a perl script to convert the serial trace into ROM access commands. The trace is incomplete, but it was good enough to start developing the script. Once I have a complete conversion script I can easily pass many analyzer trace dumps to it and try to decode what's going on. However, my first pass looks pretty daunting. These chips hold 700 bits of data organized into 50 14-bit words. I was assuming that there would be a lot of unused space in the ROM as even counting at the 'tic' level (Pulses from the speed sensor), you probably don't need that many bits to hold a number up to 200K miles or so(I've believe that I read that these "roll over" somewhere in the 200K range, possibly equating to whatever 100,000 Kilometers is in miles. There seems to be a LOT of data in use, though. More than it would appear to just hold the main ODO and if stored in there also, the trip odo. There may be some funky encoding scheme going on, or maybe multiple copies in a rotating buffer with pointers and the like to attempt recovery of a corrupt reading? It looks alot more complicated than I was originally hoping.

My plan of attack is to use my bench 12V supply with my spare cluster, which I have already sucessfully been able to feed a square wave to to simulate speed sensor pulses and rack up miles on the ODO (As well as exceed the speed limit!) I'll do several rounds of Racking up miles and saving traces that are both read and written to the ROM, including iterations where I only feed a single speed 'tick' to the cluster to see which bit(s) change from one round to the next along with the recorded ODO reading for that trace. Hopefully, with enough data collected, I'll be able to reverse engineer how the miles are stored.

My take on the * (Asterisk) that appears on some clusters is that the symbol is the electronic equivalent of "Not actual miles". I've heard that when you "roll over" the cluster, it starts at zero only with the asterisk. And when you get a new chip from the dealer it also starts at zero and has the asterisk. I also think I've heard evidence that a cluster that has been corrupted, but not to the point of the "------" of death, will also show the asterisk. I'll see what I can find out about that as well. Once I have a theory on the encoding; I can program test ROMs and see what the cluster reading looks like for different programming. I too have a schematic for a ER14xx programmer from a Russian website. I'm going to modify the design a little as it uses a coil type step up transformer to make the -37V programming voltage required. (For you EE2 out there - It takes a 12V DC, feeds it to a 555 as an oscillator to make it 12V AC, the off to a transformer to step it up to 3X or 36V, then MINIMAL filtering with a Diode and Cap. Looks pretty sketchy from a noise perspective and bulky with the transformer. I plan to find a suitable switching boost regulator to make a cleaner programming voltage)

I have a handful of ROM chips, but they are ER1400, which are 100x14 instead of 50x14. I believe that they will work fine, though and just have the upper 50 words unused as the access is random anyway and not sequential. ER1451's are impossible to find and even the ER1400's I have come across are getting expensive($25-$30 per chip) as there apparently is some demand for these in the vintage arcade game market. So, another project I plan to try is to make a small FPGA controlled emulator that will make a modern serial flash chip behave like the ER1400. Not really expecting to save cost here though, but it will make a bountiful supply chain available again, and with the plus if not needed the -36V supply at all! Also, I could make a programming "Back Door" that will make it easier to flash the mileage since most potential customers will need a custom mileage from their existing vehicle programmed in.

There will be waivers on use of course, but with the age of these cars, no one is going to really profit from false odometer readings. If the car has 200K on it, it's going to show - EVERYWHERE. And if a car looks like crap, but claims to have 40K on it, I'm paying on the actual condition anyway. Believe me, I've seen quite a few supposed low miles cars that looked like crap so there's no way I would have paid a premium on them anyway. Condition is everything when cars get to be this age. Still, there will be some waiver of liability on my part if someone provides false mileage for their chip. I'd really just be selling them a ROM with some arbitrary data requested by the customer in it and no guarantee of the usefulness or even the end use of the data provided.

On a side note, I'm also planning a re-engineering of the 84-87 Logic Module controllers. I believe that with modern technology applied to these old cars, not only can you provide better performance, but also smoother engine running. I believe the reason some of these older ECU based cars aren't as stable as their modern counterparts is the fact that the older, slower CPUs can't adjust to changing conditions as fast as newer, faster ECUs can. I'm probably going to stick with 8-bit for now, though as I'll have to port the existing source code and then tighten the loop timing and scale everything appropriately. I should be able to provide a 10x tighter control loop which should greatly improve engine response and still fit a few extra goodies like logging in. Since I'm in SMOG controlled California, the ECU will need to behave like a factory unit when hooked up to the tester's equipment, so that will be a challenge. Maybe I'll have a "SMOG Mode" switch. However, I expect the replacement computer to allow for lower emissions than stock, so I may even go after CARB certification. I'm sticking with the older LM units for now because (1. They're located in the passenger cabin and won't need to be underhood resiliant. 2. They are basically just the Brain, with the Brawn in the power module under the hood. And 3. All of my Turbo Dodges are LM equipped). Other people are working on SMEC and SBEC designs anyway, so I won't be duplicating other's efforts. I'm actually hoping to have the time to create a complete suite if interacting components to replace the electronics on my '84 Laser Digital Dash/31 Function Monitor/12-button Nav equipped car, with a single computer doing all of the work including the ECU and the Dash, Monitor, and Nav just being display units accessed by the main computer. The replacement equipment will be a combination of LED and LCD to replace the Vacuum Flourescent original displays. We'll see how far I get, this could take a while. The Odo Chip is a nice start, though and get's me working with my newly acquired test equipment. http://www.turbododge.com/forums/images/smilies/extras/hello.gif
 
#35 ·
I have been trying to help a friend with one of these dash replacements. Chips are on order from eBay. Any of the little Arduino boards can be used as a programmer. I can send the software if anyone is interested. Three 9-Volt batteries in series supply the negative bias. I've been able to read or write to any of the 14-bit words. I have a picture of the test setup and scope traces, but it seems this site does not allow attaching pictures?

What I'm wondering is, has anyone found the correct format for organizing the mileage data? Somehow the information is packed into six, 14-bit, words. Is there any error correction or check sums? Encryption?
 
#37 ·
OK, so I am bringing this thread back to life...

My 86 turbo Z just started to display "--------" in the odometer display of the digital dash. WTF?

I read through this entire thread and it seems that this is sometimes an indication that the digital dash has a short or a fault that may or may not be causing this or may or may not have shorted the mileage/odo chip out. I do notice that the push buttons on the cluster all apparently need to be replaced...and I am wondering if maybe one of these buttons might be stuck permanently in the pushed down position.

I dunno...comments welcome!
 
#39 ·
bump

OK, so I am bringing this thread back to life...

My 86 turbo Z just started to display "--------" in the odometer display of the digital dash. WTF?

I read through this entire thread and it seems that this is sometimes an indication that the digital dash has a short or a fault that may or may not be causing this or may or may not have shorted the mileage/odo chip out. I do notice that the push buttons on the cluster all apparently need to be replaced...and I am wondering if maybe one of these buttons might be stuck permanently in the pushed down position.

I dunno...comments welcome!

UPDATE: Apparently the mileage does show occasionally when driving but hit a bump and it goes back to "---------" There is no "*" present and there is no dealer cluster replaced sticker on the door jam.
 
#40 ·
Now that's odd behavior! If the ------ was persistent, I'd say you simply have a "worn out" or corrupted ODO chip. These chips are pushing 30+ years old and are going to start failing more and more often. However, I'm soon to be releasing a product that replaces the chip with a modern +5V only micro controller based chip(see my other thread).

But since yours intermittently comes back to life, there must be something else going on. Anytime the cluster powers up without valid ODO ROM data, you will get the dashes, so yours seems to not be corrupted. It's more likely that you are dealing with an intermittent open circuit rather than a short circuit. The buttons on these clusters would not cause this particular issue, but there is a way to replace the switches with nice tactile "clicky" feel replacements. I've done that on one of my clusters and it works great.

Your open circuit is most likely caused by a failed solder joint, or possibly a leaking electrolytic capacitor has corroded a circuit trace.

When you mileage starts working again, does it continue exactly where it left off the last time it worked? The best way to gauge that would be to clear the trip ODO next time it works and power cycle the cluster to make sure it sticks.

Besides the ODO ROM replacement modules I'm making. I'm also working on a nice LED display panel and soon after that, I plan to create full costume replacements for the trio of electronics in the dash(Cluster, Monitor, and Navigator). I'm just trying to figure out what people would pay for such a thing, since it won't be cheap to make in low quantities.

Anyway, if you get some more characterization of the problem, I'm happy to help in any way I can. :D
 
#41 ·
Hey that is great, I just took possession of the car and I will have to make note of the conditions you've suggested and get back to the post/thread on my observations. I ordered a set of new switches yesterday from Mosler and they will be here in a few days, I'll have to pick an afternoon to install them and look for anything that looks out of the ordinary like poor connections, broken solder pads, and leaky capacitors as you've suggested. Depending on what I come up with, I might be among your first clients or a good candidate for a beta tester.. ;-) (wink, wink) I might also be a good place to offer your products for sale. (turbododgeparts.com)
 
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