I had installed a 88GTA digital dash into a 91 TBI 305 Formula, and had it working for a brief time. However I was going to change it back to the stock dash since I couldn't get it illuminated enough. Before I got to that the gauge fuse blew, and when I replaced it everything was working again except the speedometer/odometer. I assumed it was something shorted in disgital dash and figured it would be fine when I put the original dash back in, it wasn't. The same thing is happening now with the stock analog gauges. I have ruled out the VSS box, fuse, and gauge cluster as possible causes, but am in need of help with suggestions of what else could be causing the sppedometer/odometer not to work. I am not sure if maybe I somehow blew out the speed sensor or something when the fuse blew. Any ideas or help would be greatly appreciated. Thank you.

 

Last week i tried using my cigarette lighter in my car and that caused the dash, odometer, and overhead light to stop working. It ended up bein a fuse that blew. Maybe its possible that you replaced the wrong fuse or maybe you blew 2 fuse. Id check again. -Austin

 

I'll double check all the fuses again, but I don't think that is it because my cigarette lighter, dome light,etc. all still work. I've had that fuse blow before and know all the things that stop working then. Thanks for the tip though, it couldn't hurt to recheck them all again. Any other suggestions would be greatly welcomed, since I really need to get this car fixed soon. This is the strangest thing that happened and so far I am really stumped on what else to check that could cause only the speed/odometer and the cruise control to go out since it's all connected. Is it possible that somehow I shorted something out in the computer maybe?

 

Please help, this is driving me f'ing crazy!

 

Also I just noticed the cooling fan doesn't seem to kick on now, on top of the previous problems mentioned before with the speedo/odometer. Is there possibly another fuse somewhere controlling these things that is located somewhere else other than the fuse box? I am at a loss for what to try and do next, please help anyone...

 

Check the "gauges" fuse.

 

That fuse did blow at first which started this whole mess to begin with. I did replace it and all the gauges work except the speed/odometer, which had been working just fine before. So something else has to be causing it not to work. I checked the tan speedometer wire for power and it appears there is none going to it. That's why I didn't know if there is another fuse attached to it somewhere that might be hidden. This is so weird that only that gauge is not working when it was fine just before the fuse blew. Please somebody let know what else to check...

 

I was reading through some past posts about trouble shooting Speedometer problems similar to the one I have, and some people indicated that a bad ECM may be causing the Speedometer not to work. Can somebody tell me if this is true about the ECM controlling the Speedometer, because I thought it was the VSS buffer box that controlled it? Is it possible that when the gauge fuse blew, that it shorted something in the ECM?

 

Any suggestions??? I really need help with this soon.

 

in reply to your post elsewhere about how noone on this board helps people ;0

so im taking it you just plugged the digital dash, into your existing analog setup, yes/no?
i dont have the digi dash pinout memorized in my head or something, but I know they are not plug and play (i didnt think they even used the same style of connectors.. *shrug*)
fuses blow to protect sensitive parts, but it mightve been to late if some wires got crossed

I doubt the VSS itself was harmed, and no the ECM does not control the speedometer and I doubt it was harmed either, however possible.. the buffer has multiple outputs to ecm, speedo, cruise

 

Hi, and thanksfor replying to my question. Yes, I cut the original connectors going to the stock analog dash, correctly rewired the digital dash connectors to it and it worked perfectly. But when I went to put permanant wire connectors on some of the wires after the test run I did, I foolishly didn't disconnect the battery and a couple wires touched and shorted out the gauge fuse. When I replaced it, everything worked but the speedometer/odometer, and I'm pretty sure the engine fan isn't kicking on but I'm not positive on that yet since I haven't drove it since this happened, just started it up a few times. I thought maybe when the fuse blew it shorted out the digital dash's speedometer maybe. However when I went back and rewired the stock gages back to normal and put it back, everything worked except for the speedo/odometer again. Since the analog dash wasn't even in the car when the fuse blew, it has to be something in the car itself. As for the buffer box, I visually inspected it and everthing appeared ok, no obvious damage on it and lookedbrand new anyway. Also I tested the speedo wire coming from it there was no indication that there was any power going through it. So could it still be the buffer box possibly, or maybe the speed sensor? PLEASE answer back with help again. Thanks so much again for responding before.

 

I dont know how to tell you to test the VSS/buffer box, it uses pulse per mile signal, 2000ppm for the speedo, 4000 for the ecm (or other way around i forget) that gets adjusted by the buffer box

it probably wont read anything on a voltmeter unless your drive wheels are spinning

hook the guages back up and drive around and see if the ecm sets an error code? or if you could datalog just check and see if the ecm is getting the speed signal

 

Ok thanks, I'll try that and see what the codes are then.