Speedometer/Odometer not working April 10, 2009, 03:00:41 PM I have an 85 Tbird, someone decided to install a stereo without an adapter harness. The Speedometer and odometer won't turn on with the key, and the dome light doesn't illuminate when the doors open either. I've seen this problem before, when I did the exact same thing in my young & ignorant days!There's no radio installed now, and I can see 2 intact plugs, one with 4 wires and 1 with 7 wires, I believe. I do have the factory stereo, but the plugs on it were cut.I guess I need to find an intact factory stereo or buy an adapter harness with an aftermarket head unit.Does anyone know if I can simply ground or apply voltage to one of the wires in the car's harness to get the speedo & odo working? I can take pictures of everything if needed.Thanks for any help! Quote Selected
Speedometer/Odometer not working Reply #1 – April 10, 2009, 09:31:24 PM what reasons lead you to think you need to do this?Its not going to help.totally different circuit, you probably have blown bulbs. You might find the EVTM useful in electrical tech. It is a sticky up top which when you open it , you have a link to all the wiring diagrams. Although the 87 EVTM is two years up on you, not too much changed. Quote Selected
Speedometer/Odometer not working Reply #2 – April 10, 2009, 10:29:32 PM If you just re-connect the cut wires to the cut harness, you should be able to do better troubleshooting. Quote Selected
Speedometer/Odometer not working Reply #4 – April 11, 2009, 07:45:09 PM Fuse 8 has continuity, so does the lamp in the dome light.The link for the EVTM diagrams seems to be missing now... I remember seeing it a couple days ago... am I just not seeing it now?I'm undoing the damage of a seriously bubba'ed hack job. Someone decided to use extension cord wiring to install a stereo.I have the dash apart and the instrument panel almost out. I ran out of daylight but I'll start checking connections tomorrow Quote Selected
Speedometer/Odometer not working Reply #5 – April 11, 2009, 09:02:21 PM QuoteSomeone decided to use extension cord wiring to install a stereo.When I bought my cat, the retarded owner (instead of replacing the stoplight switch) used extension cord wire and a house light switch, to rig a toggle for the brakes. He twisted the wires seperatly (ground and lead, I guess) then twisted them together and taped them - with both wires touching, and told me "I don't know why it dosen't work...." What an ass, people that do shiznit like that shouldn't be allowed to own cars..... Quote Selected
Speedometer/Odometer not working Reply #6 – April 11, 2009, 09:53:05 PM humm,, the radio wiring somehow has an effect,, your cluster isnt getting power but many of us have been fooled by bulbs.lets see,, Does the speedo light up at all? or is it dead as night?Fuse 8 sends power to the speedo on the LG/Y wire directly with no relay involved whatso ever.Problem,,-you will have to remove the cluster to confirm it has power up to the connector C246 pin 17, but hold off and continue reading. I think i can see where you might find a shortcut to figuring this out.The LCD illumination is controlled by the white/light blue wire.The W/LB wire travels across the contacts of the illumination relay and changes colors to White pink moving to its fuse 6.Lets assume the relay powers up.Your power source for the LCD display would be fuse 6 on the white pink wire.Lets assume now the illumination relay is not getting power or is missing.Find the relay located on LH side of instrument panel near main light switch.next verify illumination relay coil input has power going to its coil from the main light switch on the Brown wire, if not..... You have a main light switch that is bad (unlikely if other lamps work.So,, the illumination relay gets its coil power on a brown wire from the main light switch.The Illumination relay gets its coil ground from somewhere land, which you can jumper it to ground if need be on the black.The input contact power W/P for the illumination relay gets power from fuse 6.* a good indicator this part is malfunctioning is the trunk light is not working.The illumination relay contact output W/LB to the LCD display will arrive at your speedo on C285 pin 16.The LCD display will obtain a ground locally somewhere in the land of ozz, or you can supply a ground to it C246 pin14 and/or 18. Quote Selected
Speedometer/Odometer not working Reply #7 – April 11, 2009, 10:33:46 PM Thanks so much for the writeup! I do have the instrument cluster loose.The entire cluster illuminates, but 2 out of the 3 displays were blank (speedo and right-side panel. gas/oil/temp panel on the left worked) I think the radio harness is OK now. Don't know why the dome light isn't working with the door open, but I still have a few fuses/breakers to check.I'll start checking the wires you mentioned tomorrow. I've been searching through the posts on this board, and others have had this problem, it might be broken contacts on the cluster's flex board. Quote Selected
Speedometer/Odometer not working Reply #8 – April 11, 2009, 10:45:05 PM okso the original post was not actually accurate. I still think there are bulbs hosed. check those out.Alos,, dead nuts center bottom of the speedo cluster, there is a narrow 1/2'' wide portion of flex wiring that is exposed. It is damaged when the top portion of the steering column cover is removed.If that part is busted, it will prevent the speedo from showing an LCD display. The background will be green but no numbers. To fix, you snip the flex print in half, peel pack the top layer of each side, jumper the solder runs with cat5 wire or some small guage wire. Thats what i had to do a long time ago when I busted my flex in the area i am describing.The lack of intensity of a green background and LDC display will be the fault of two bulb at the top back of the speedo module. Quote Selected
Speedometer/Odometer not working Reply #9 – April 11, 2009, 11:12:43 PM I apologize for not being clear in my original post. The steering column cover has obvious signs of being removed & roughly handled. It wasn't reinstalled properly. I'll pull out the cluster and check the flex printI think the bulbs are OK, but this is the best opportunity I'll ever have to check them. Quote Selected
Speedometer/Odometer not working Reply #10 – April 12, 2009, 09:59:19 AM ok,,throttle back,,do you have a full digital cluster?ordo you have an electronic speedo with buttstuffog fuel temp needles? Quote Selected
Speedometer/Odometer not working Reply #11 – April 12, 2009, 05:23:13 PM Full digital clusterThe flex print all checked good. However, one of the traces looked different, like it overheated while pulling a lot of current. It still had continuity though.I can tell that the cluster has been pulled before. The right connector wasn't properly seated. The right hand display works now (display with fuel economy, miles-to-empty, etc.)Unfortunately the speedo/odo are still blank, but properly illuminated. Quote Selected
Speedometer/Odometer not working Reply #12 – April 13, 2009, 12:02:23 AM okfull digi clusterfollow with the previous instruction on the Illumination relay so power can get to the LCD display.Ill be no where near my books the remaining of the week (ill be in Venice, Ft Myers and Naples FL). softtouch, Turbocoupe50, Thunderchicken or Master Blaster can run with it. If you search,, I think there has been a post in the last 6 months were the symptom was now where you stand.That symptom was the LCD illuminated but no numbers displayed.I posted up the troubleshooting proceedures for it and honestly, i think it leads to replacing the speedo module. the modules arent that hard to find, the full digi cluster is though.I suspect that the information i gave you may be a little off because we are just not learning you have a full digi cluster. wish i had known that first off, could have prevented lost time. Quote Selected
Speedometer/Odometer not working Reply #13 – April 13, 2009, 10:39:45 PM If I can find a cluster with the digital speedo and buttstuffog gauges, I'm sure I could pull the speedometer module out of it and solder it into my full digital cluster. I do that kind of stuff for a living, and would love to take pictures of the repair for the benefit of this forum.I would still like to check for power/ground/signals at the connector plug in the dash. What happened to the EVTM link? It says "forwarded to public link" now, I'm not sure what that means. Quote Selected
Speedometer/Odometer not working Reply #14 – April 13, 2009, 10:55:17 PM while you are at it.......do this...........http://www.coolcats.net/tech/advanced/199speedo.htmlEveryone else here has!!I cant find the 199 speedo mod link as in all the pics that came along with the work up of it.help anyone? Quote Selected
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