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So I'm just getting this thing idling and driving down the road, made some adjustments, downloaded everything to the emulator then all of the sudden, my MPH starts reading the same as the TACH, then stops. As I go for a drive, no VSS reading in tunerpro, and no transmission shift. It's a 4L80E and a 7060 PCM. Did I just witness something in the ECM committing suicide or did the VSS itself just die? Oddly enough the electric speedo still works.
If you're running the speedo from the same sensor, then the sensor itself is fine. Check over connections to the ECM, if you can't find anything there, swap to another ECM.
However the speedo is driven in a factory stock truck. I think the signal is split at the DRAC, one signal goes to the PCM and the other to the speedo, but I'm not sure.
If you're running with a DRAC (VSSB to some) and the speedometer works, the VSS should also be working. Either the DRAC output to the PCM failed or somethings up with the PCM itself. As mentioned, swapping PCM's would be a good start.Quote:
Originally Posted by 1BadAction
1991 Square body Suburban? You sure the VSS is not in speedo? Not sure with all the changes and yours is 4x4, but speedo is cable driven and VSS is in Dash.Quote:
Originally Posted by 1BadAction
Could be as simple as a fuse...
http://www.gearhead-efi.com/Fuel-Inj...0&d=1331728025
Mine is a 2wd, nothing electrical has been changed from stock. 91s no longer had a cable drive speedo or optical eye vss on the back of the gauge, they had the electronic VSS on the transmission.
It very well could be a fuse, I may be getting excited about nothing.
Ah forgot you were 4L80E... my bad...
Well, verdict is, either it is the EEPROM or the ECM itself. I'll be ordering an ECM complete with prom this week and checking it out next weekend.
Has anyone had trouble with reman computers? This one was already replaced once.
Your first post said emulator, sometimes things go bad there, just takes a restart, upload verify and emulate to make it right.
I've never had an ECM/PCM go bad and never got a bad one from JY, so I can't comment on new ones. VSS would be a more likely suspect.
if you look in my previous posts, I had the same thing happen to me a few weeks ago. 7060/80E 454. speedo still worked, trans didn't shift.
http://www.gearhead-efi.com/Fuel-Inj...ll=1#post20340
Durning my tuning and programming with my burn 2, I ended up somehow loosing VSS. I also had a code 51 which EagleMark had showed me (it had been there awhile). And I still have this weird datastream glitch.
During this extremely frustrating day of tuning, I could not get the VSS signal back by programming. I thought it was just a flash error because how could it just all of a sudden loose the VSS?
Local autozone had the computer for $99 instock. Snagged it, installed my G3 and flashed a new chip. Bingo, Everything works again.
For some reason I still have my doubts that it was the computer for sure.....but the reman computer did fix my issue so IDK WTF.
This is really really odd that you have the same issue as I just had with the same setup....although you're emulating.
Yes, it was during emulation... When I parked it, it was running like crap, throwing codes, not responding to anything. So last night I checked fuses, then uninstalled everything and put the computer back to stock. It wouldn't even start and run in limp home. Codes wouldn't clear, no response at all.Quote:
Originally Posted by EagleMark
Very strange we've had the same problem, indeed. I wonder if it's just the old electronics? I'll see what I can find locally. I did pull the pcm so I'd have a core.Quote:
Originally Posted by chevmasta
Hopefully it's not the EEPROM
It can't be the EEPROM during emulation and everything you said above is a sure sign something happened to emulator. SOmetimes it just happens, you need to learn the signs like above. Reload the bin to TunerPRo, Upload to emulator, Verify, Emulate, turn key on and should come on, blink and stay on till started.
Did you set Mask ID to AA to disable checksum?
Yes, I agree, but to diagnose it, I took out the G1, installed the stock prom, and tried it that way. Wouldn't even start. I set the PCM into limp home a couple times when emulating. I just shut everything down, waited 30 seconds, then started it back up seemed fine until right before I stopped messing with it last saturday.Quote:
Originally Posted by EagleMark
That explains why it would still run (albeit setting tons of codes) while emulating, but wouldn't run at all when I put the PCM back to stock. Sounds like it's the eeprom itself and not actually the PCM that is the problem.
How do I set the mask ID? That should fix the issue with emulating. I think the killed PCM was my own ham-fisted fault...
Open Mask ID and change from 85 to AA.
You probably have a error 51 Prom Failed set in PCM, clear codes and try again. If 51 is set it won't run right even if you fixed the issue until codes are cleared. Emulating without AA sets error 51.
Whenever I hook up to data first thing I check is Error codes.
The computer holds that code even though it's physically unplugged?
It will clear if unplugged/power removed. But if you emulate without AA it could set real fast again. Testing is cheap compared to a new PCM...
Open your bin, save your bin as TP will calculate checksum, then change mask ID to AA, save bin, then do the upload, verify etc...
I had the PCM unplugged when I swapped to the stock EEPROM. Still a bunch of error codes.Quote:
Originally Posted by EagleMark
I can't find where to change mask ID. It's not in scalars, is that where I should be looking?
In this XDF where I added it... :innocent2:Quote:
Originally Posted by 1BadAction
make sure to throw that file in the 7060 thread! :)Quote:
Originally Posted by EagleMark
http://www.gearhead-efi.com/Fuel-Inj...Information-85
:doh:Quote:
Originally Posted by EagleMark
Thanks for the upgrade. :happy:
Done! :thumbsup:Quote:
Originally Posted by chevmasta