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.

[quote:4d27cc94b7="saturntech9"]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.[/quote:4d27cc94b7]

I completely switched out the speed sensor for a new one and it didn't make a difference. The only code that comes up is 26 which the book says is the quad driver module. I've also checked the TPS with a volt meter and that seems to be working fine. However this is the first time anyone has mentioned anything about the seat belt which have occasionally been acting up. The only thing they are doing though is rolling back when the key is in and turned to run. That and the chime for the lap belt starts. This only happens occasionally though.

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.

[quote:54851bc906="saturntech9"]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.[/quote:54851bc906]

Makes sense, is that something that can be checked with a meter or anything? And how would I go about repairing it or replacing it

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.

[quote:062c338b84="saturntech9"]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.[/quote:062c338b84]
Ok so I did that and it seems to work how its supposed to. Pretty much as soon as I hit the gas the belt closes. whats 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.

[quote:dfc4015601="saturntech9"]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.[/quote:dfc4015601]
Ok so I've found a black box with the letters TRW On it. It is cracked and covered in dust and crumbs but not sticky at all.

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.

[quote:2042d8a347="saturntech9"]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.[/quote:2042d8a347]

I have a hard time reading the diagram, it shows up kinda blurry. I could not find anything that was labeled with an H and two of the connectors have a dark green wire with a white tracer on it. I tried disconnecting them one at a time and seeing if the speedometer worked but it still did nothing.

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.

[quote:7c2cb03f0d="saturntech9"]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.[/quote:7c2cb03f0d]
I printed the diagrams, They are still fairly blurry, however im not sure i'd be able to understand them either way. I disconnected both the connectors with the green wire and white tracer and tried it again. Still nothing

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.

I found two green and white wires again. I tested both of them. one did absolutly nothing. The other with the car on and idling had about .003 for the voltage and increased when in gear and gas was pressed.

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.

[quote:52ed2c6baa="saturntech9"]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.[/quote:52ed2c6baa]

Ok and what would be the easiest way to find and fix that problem

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.

Sorry it's taken a few days to reply. Ive had to work a lot and couldn't get around to my car. However the multimeter I have only has ohms volts and something else would it still work for this or do I need to buy a different one? Also could u help u help me out with understanding which is the A terminal and the C terminal?

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.

[quote:7944bc021e="saturntech9"]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.[/quote:7944bc021e]
I tested terminal A with the key off and it's giving me about ten and a half volts. With the car on it gives 12 volts. I'm having trouble with terminal C though. Does it need to be unplugged too? Or can I just insert the pin in with the wire while it's plugged in? Doing it that way gives me a reading that jumps all over the place from .339 to 155.0 and the measurement switchs between M ohms and k ohms

The connector should be unplugged from the fuse box when testing it.

[quote:805acceef9="saturntech9"]The connector should be unplugged from the fuse box when testing it.[/quote:805acceef9]
Ok so I finally got it unplugged and tested the ohms between terminal A on the dash cluster and terminal C from the cluster on the fuse box. It's pretty steady from .2 ohms to .5 ohms

It's beginning to look like you have a bad speedometer.Try what i posted and emailed you by checking that A terminal at about 60 mph for voltage it should read half of battery voltage.You don't have the cruise cluster tester so you will have to improvise by spinning the tire's at about 60 mph with the tire's safely off the ground.They are selling one of those cruise cluster tester's on ebay though.

I havnt had a chance to test that yet however I believe the speedometer itself is working. Earlier in the week a friend of mine said to try running my own wire from the dark green and white one that goes to the passenger restraint system strait to the speedometer. When I tried that the speedometer went up to thirty but that's it. I'll still let u know how the whole going sixty on jacks thing turns out though

I havnt had a chance to test that yet however I believe the speedometer itself is working. Earlier in the week a friend of mine said to try running my own wire from the dark green and white one that goes to the passenger restraint system strait to the speedometer. When I tried that the speedometer went up to thirty but that's it. I'll still let u know how the whole going sixty on jacks thing turns out though[/quote:1093e185e0] I measured the voltage while the wheels where spinning at what i think would be around 60. It said to be about 7

It's looking like the speedometer the trouble tree say's half of battery voltage and 7 volt's is about half when the car is at 60 mph.But you said it got to only 30 mph when you jumped it from the seat belt relay.Try jump it from the ecm to speedometer instead of it going thru the fuse box that way you will know your problem is from the ecm to or thru the fuse box.

[quote:4009738e1b="saturntech9"]It's looking like the speedometer the trouble tree say's half of battery voltage and 7 volt's is about half when the car is at 60 mph.But you said it got to only 30 mph when you jumped it from the seat belt relay.Try jump it from the ecm to speedometer instead of it going thru the fuse box that way you will know your problem is from the ecm to or thru the fuse box.[/quote:4009738e1b]
I couldn't find anything about an ECM on my car so I assumed u ment PCM and used the wire going from that to the fuse box to jump strait to the speedometer. After that I drove the car and again the speedometer went up to thirty and stopped. However I noticed that if I drove it past thirty mph and slowed down the needle seemed to stay at thirty until it the speed went down to thirty and then the needle moved down with the cars speed.

You have a ecm a pcm mean's you have a automatic transmission and the computer for the engine and transmission are combined.It's looking like a bad speedometer if it stop's going up at 30 mph what if you smack the dash will it go up higher then 30 mph?

[quote:dc023c997c="saturntech9"]You have a ecm a pcm mean's you have a automatic transmission and the computer for the engine and transmission are combined.It's looking like a bad speedometer if it stop's going up at 30 mph what if you smack the dash will it go up higher then 30 mph?[/quote:dc023c997c]
I took the car out for a drive with my whole instrument cluster unbolted. I tried shaking it, hitting it, turning it over etc. The speedometer stayed at thirty. However i did notice that as soon as I turned the car on the temp was 3/4 the way up and moved back and forth whenever I put the right blinker on

It's getting stranger by the min but it's looking like a bad speedometer since your getting a good speed input and it only goes to 30 mph.

[quote:026b00cc45="saturntech9"]It's getting stranger by the min but it's looking like a bad speedometer since your getting a good speed input and it only goes to 30 mph.[/quote:026b00cc45]That's if I jump it though. What about when it's not jumped and it does nothing? Or can I just leave it jumped and put an inline fuse to protect it if I get a new speedometer and it works?

Since you checked and got a good connection from the fuse box to the speedometer then you must have a problem from the computer to the fuse box or where the computer wire connects to the the speedometer wire at the fuse box.