1994 Saturn SC1 Speedometer

How do you know the speed sensor is good how did you test it?Also do you have a any code's?You probably have a bad seat belt module under your center console that control's your power seat belt's. The speed signal has to go threw that module before it get's to your speedometer.

The seat belt module is part of that quad circuit and a bad one will set a code 26 and or a code 27 quick quad fault. The reason the speed signal goes threw it is because when the car reaches about 13 mph the power seat belt will close if the drivers door is open if the seat belt doesn't close and the seat belt close's other wise then you have a bad seat belt module.

They way I check them is put the car up on the lift with the front wheel's off the ground with the driver's door open put the car in drive and spin the wheel's to about 20 mph and if the drivers power seat belt doesn't close then you have a bad seat belt module. If you have a jack and jack stand's you could raise the front wheel's off the ground with the ebrake on and the rear wheel's blocked. Why don't you do that to see if the seat belt close's and let me know what you find and we will talk about what to do next.

Alright the speed signal is going into the seat belt module but we don't know if the signal is coming out of it. The problem i'm having is I can't find a wire diagram for the speed signal circuit to tell which wire's go where if memory serve's right I think it goes from the seat belt module to the inside fuse box to the speedometer. The way I always test it is I have a tester seat belt module I swap it with most of the time it work's and tells me that the old one is bad. Let's try this under your ebrake handle pull your ebrake all the way up. You will see a access door pop that off then look into the hole you will see a black box that is your seat belt module see if it's cracked or all sticky and look's like thing's were spilled on it. Let me know what you find.

I emailed you some wire diagram's let's try this unplug the connector to the seat belt module that has the dark green wire with a white tracer on it the wire will be terminal H labeled on the connector. Then see if your speedometer work's. Let me know what you find.

It say's to print it for better viewing try unplugging both dark green wire's with white tracer's at the same time and see if the speedometer work's.I see a speed input going into the seat belt module but not one coming out so what I think happens is when the module's take out the speed signal that it just sap's that signal down so the speedometer doesn't work. Let me know what you find and we will go from there.

I'm also emailing you a copy of the wire diagram that i posted.The speed signal run's from the pcm to the inside fuse box then it split's off to the seat module, cruise control and the speedometer.Your going to have to remove the dash top there is two dash cover cap's that cover the screw's pop those off.Then remove the screw's there 7mm then work a big flat headed screwdriver along the outer edge of the dash facing you and pop up the retaining clip's.Make sure you stay close to the retaining clip's when you pop then up.Then you will tilt the top up and slide it out of the of the slot's that are by the windshield.I emailed you how to test if the speed signal is getting to the speedometer instead of using the cruise cluster tester which you don't have you will have to spin the wheel's on jack stand's while checking the dark green and white wire for voltage.You have a bad speedometer or your not getting the speed signal from the inside fuse box.

It say's that you should have half of your igniton voltage to that wire. It look's like the wire your looking for is terminal A on the cluster connector so that would be the end one. It sound's like you have a break in the wire from the inside fuse box to the cluster.

What you should find with the key in the lock position check the dark green and white wire the one on the edge of the connector which is terminal A with the cluster unplugged it should read battery voltage.That is the speed input for your cluster.Now if you go to the back of your inside fuse box you will see large black 68 way connector above that there is a smaller connector with 4 dark green wire's coming out of it.Unplugged it then put your multimeter on low ohm's scale like the 200 ohm setting.Check between the A terminal at the cluster connector with it unplugged and the C terminal of the small connector the terminal side of the connector.Let me know what you find.

I also emailed you a copy of the wire diagram so you can see the terminal's.

Your volt ohm's meter will work for testing start by putting it on dc volt's then with the key off unplug the cluster you will see two dark green wire's with a white tracer one will be the last wire on the end of the connector like I told you before. That is terminal A on the cluster connector that should have battery voltage. Now put the meter on ohm's and check the reading from terminal A of the cluster connector to terminal C of that other connector I told you about the connector should be labeled.