No Speedo/odometer
Thread Starter
Member
Joined: Sep 2007
Posts: 172
Likes: 0
From: Southampton, MA
Car: 89 Firebird Formula
Engine: 305 Vortec, Single-plane, 4 barrel
Transmission: T5, soon 700R4
Axle/Gears: 88 10 Bolt, Disc, Auburn, 3.23
No Speedo/odometer
Hey guys,
I got a question for anyone that can help me. I've got an 89 formula 305TPI.
I just bought it a few weeks ago and I'm trying to nurse it back to health.
Anyhow, the speedometer doesnt work (nor Upshift light, bulb good, lights in diag mode). I change the trans fluid(T5) and checked the Sender (electronic VSS). Gear was there, not worn, hooked up the VSS to an ohmeter and turned it, it bounced around a bit so I figure it works. I think it was like 450 or 4500 ohms stationary and really low (towards zero) when turned.
I hooked up a voltmeter to the wiring from the harness but all I got was like 30 millivolts. The car was off though with the key turned on; perhaps the engine would have had to have been running though.
I pulled out the cluster to find a connector that is integrated to the dash.cluster and is not like a pull apart connector, it's just like a contact connector. So I wasn't able to do any testing cause I didn't know what color wires were on the back and I wasn't gonna drive down the road testing each one.
So, what would be some preliminary checks for the system? I'm wondering if my ECM could have a bad ground. I tested the grounds on the MAF relays and some unknown relay near the brake master cyl and got 9-10 ohms ground resistance, yuck.
My engine also runs like **** even though I've done on the mechanical maintenance (oil, pcv, air filter, cap rotor wires plugs, belt, etc, etc.) But that's a whole nother story.
Thanks in advance for any help.
-Dave
I got a question for anyone that can help me. I've got an 89 formula 305TPI.
I just bought it a few weeks ago and I'm trying to nurse it back to health.
Anyhow, the speedometer doesnt work (nor Upshift light, bulb good, lights in diag mode). I change the trans fluid(T5) and checked the Sender (electronic VSS). Gear was there, not worn, hooked up the VSS to an ohmeter and turned it, it bounced around a bit so I figure it works. I think it was like 450 or 4500 ohms stationary and really low (towards zero) when turned.
I hooked up a voltmeter to the wiring from the harness but all I got was like 30 millivolts. The car was off though with the key turned on; perhaps the engine would have had to have been running though.
I pulled out the cluster to find a connector that is integrated to the dash.cluster and is not like a pull apart connector, it's just like a contact connector. So I wasn't able to do any testing cause I didn't know what color wires were on the back and I wasn't gonna drive down the road testing each one.
So, what would be some preliminary checks for the system? I'm wondering if my ECM could have a bad ground. I tested the grounds on the MAF relays and some unknown relay near the brake master cyl and got 9-10 ohms ground resistance, yuck.
My engine also runs like **** even though I've done on the mechanical maintenance (oil, pcv, air filter, cap rotor wires plugs, belt, etc, etc.) But that's a whole nother story.
Thanks in advance for any help.
-Dave
Senior Member
iTrader: (14)
Joined: Oct 2006
Posts: 823
Likes: 1
From: erlangen, Germany
Car: 1991 Z28 1LE
Engine: LS1
Transmission: T56
Axle/Gears: 3.42
Re: No Speedo/odometer
My car ran very badly before wiring up my T56 VSS ( poor idle, poor acceleration)
Here is a link for wiring diagrams http://www.autozone.com/az/cds/en_us...rInfoPages.htm
It is a lot more in depth than Haynes service manual.
I had to use a SGI-5C box to re-calibrate my signal but you shouldn't have to do this since you already have an electric speedometer. But if you don't feel like tracing wires you could use this box to re-do your factory wiring. I wired my VSS into it and hacked into the wire on my ECM and ran another wire to my speedo. Just an option.
Here is a link for wiring diagrams http://www.autozone.com/az/cds/en_us...rInfoPages.htm
It is a lot more in depth than Haynes service manual.
I had to use a SGI-5C box to re-calibrate my signal but you shouldn't have to do this since you already have an electric speedometer. But if you don't feel like tracing wires you could use this box to re-do your factory wiring. I wired my VSS into it and hacked into the wire on my ECM and ran another wire to my speedo. Just an option.
Last edited by mcgarnicle; Sep 29, 2007 at 10:23 AM. Reason: none