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#1 |
![]() Join Date: Feb 2010
Location: Summerfield, FL
Posts: 434
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I have no speed, no mileage (odd) no instant or avg mileage. tbl codes are
32,34,36,38. clear codes still not working. sys lite flashes at times. car starts runs ( ran 7.72@92 mph at points race this past weekend 1/8 mile track. I'am using a tech 2 , check veh speed no reading on tech 2. per fsm 1990 section 8D pg 36 ? possible replace ccm/bcm. or can it be tested to see if it is ok? car has an auto (4l80E) so i can see mph on the transmission control unit. thanks john 1990 white/black #2546 one of a few auto 4l80E eq zr-1's |
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#2 |
![]() Join Date: Jul 2007
Location: Bartlett, IL
Posts: 7,165
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I wonder if the speed sensor is not working. Sys light flashing could be no communication with ccm/ecm
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1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Shelby Series 1 - Wilwood Brakes Custom Interior NCM Lifetime Member #978 |
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#3 |
![]() Join Date: Oct 2004
Posts: 1,884
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Do you have anything in the speedo/odo LCD? If yes do your CCM checks from the DIC and see if it confirms them. I'd think yes. Everything pretty much addresses shorts to ground or an open circuit in the CCM.
The DIC diagnostics routine is here: http://tech.corvettecentral.com/2011...trouble-codes/ Connector issue? Has the cluster been removed recently? I'm guessing since the 4L80E has been there for a while that they did function at one time or another. Yes? To get the speedo/odo display operating originally I'd guess they needed to use a DRA to establish the signal OR there are tail-shaft housings that have been modified to use the mechanical gear drive/driven VSS. Which is used in your car? The 4L80E never had a mechanical drive/driven arrangement. That's where I'd start - whatever was done to get the signal from the 4L80E to the CCM. |
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#4 |
![]() Join Date: Feb 2010
Location: Summerfield, FL
Posts: 434
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update,
checked VSS wiring up to the ECM yellow plug pin 5 connectivity from the toss signal . The toss signal is a reproduction of VSS signal to use for ECM. The VSS is used by the trans controller for controlling the trans. Now about 2 months ago i had SYS flashing on the speed/odd display. Checked the codes for the CCM , codes H32- H34-H36 and H38. Cleared codes they did not return.This time the codes remained. Turns out that i found the ground wire for ratio adapter to be loose causing the loss of MPH ODD, trip mileage etc. remade ground connection will test later, 98% sure that is my trouble. so no ground to the ratio adapter, no sig to ecm. Thanks for the help John 1990 white/black #2546 one of a few auto 4l80E eq. zr-1's |
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#5 | ||
Join Date: Dec 2012
Location: NC
Posts: 1,783
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Following this thread here John - I got one odometer digit with 'shaky' display - the '3X,000' digit (and put in the 4L60e).
Quote:
And this part I'm lost on too here... Quote:
![]() Last edited by Schrade; 09-19-2013 at 11:06 AM. |
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#6 |
![]() Join Date: Feb 2010
Location: Summerfield, FL
Posts: 434
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OK last update,
Just came back from test drive everything is working. Speed/ood instant mile per gal, avg mile per gal, trip reading. back ground car 1990 zr-1 with 4l80E transmission using compushift transmission controller. the compushift controller uses a signal call TOSS (transmission output speed signal). this signal can be used to send inputs to your ecm. Now i use a transmission raito adapter to sent toss sig to the ecm, but it goes first to raito adapter.The unit has ground,+12v , sig in from toss and sig out to the ecm. Well they don't work very well when you lose ground connection. therefore no ground no sig to the ecm from the raito adapter. In an early post i said that about 2 months ago sys lite was flashing, but i did not lose my speed/ood etc. when pulled the codes from the ccm/bcm they were h32,h34,h36, and h38. cleared codes and they did not come back. But with the ground being loose (all the time i lost my sig). Repaired loose ground connection now everything works. I have been working on an auto trans install since Aug.2004. since then i have broke 2 4l60E's and 1 700r4 too much HP. so i installed an 4l80E out of a 3/4 ton chevy truck. had it rebuilt with 2:75 1st gear 1:57 2nd gear 1:1 3rd gear 4th gear .75. rear end gears are 3.73. @ 70mph i can get 20mpg in cruse mode. around town 15-17 mpg. At the track best run 11.58@120mph and during hot weather i run 11.70 to 11.88 @ 117 mph. So it was the VSS sig in a way, signal was good but the ratio adapter did not see it. hope i made this clear to everyone who helped me with things to look at. thanks John 1990 white/black #2546 one of a few 4l80E eq ZR-1's |
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#7 |
Join Date: Jul 2013
Location: Central Iowa
Posts: 188
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I had the same issue with the ground by the stereo this week. Same no display results, no function of the trip/reset buttons etc.
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#8 |
Join Date: Dec 2012
Location: NC
Posts: 1,783
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You have the same wired-in radio adapter ground, that aafc has???
![]() ![]() ![]() Or is yours, emmvette, a factory harness ground? Is it in the schematic above? Last edited by Schrade; 09-20-2013 at 07:12 AM. |
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#9 |
![]() Join Date: Feb 2010
Location: Summerfield, FL
Posts: 434
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When i installed the auto trans in my car i used an after market electronic
ratio adapter between the vehicle speed sensor and ecm. the unit has 4 wires black to ground red to +12v white output from vss and blue input to ecm.(see FSM section 8A-33-0). The yellow wire is cut and the ratio adapter wired in place. This unit was install back in Aug. 2004 when i started the auto install. NOTE! only the yellow is connected to the ratio adapater per cust help desk.Also the vss is called TOSS (transmission output speed sensor) from the compushift wiring harness. so i'am not using the permanent magnet generator shown in the FSM sec 8A-33-0. hope this info helps. John 1990 white/black 2546 one of a few auto 4l80E eq ZR-1's |
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#10 | |
Join Date: Dec 2012
Location: NC
Posts: 1,783
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![]() Quote:
![]() And now I'm curious what emmvette had goin' on there... |
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