Resolved 1993 Cobra SRS Crash Sensors Front Right and Front Left

[jeremyzcook82]

I just bought a 1993 Cobra. The airbag light flashes 4 times, pauses, then flashes 4 times again. The code shows RH crash sensor. When I looked at both the LH and RH, they both have same number on sticker, F2ZB-14B005-AA. Is this correct or should they be different numbers? If they are the same, does that mean the front left and front right crash sensors are interchangeable? Need help to pass inspection to get it registered.

 

[Noobz347]

They are the same sensor.

 

[jeremyzcook82]

Thank you. I took a picture of them

 

[AeroCoupe]

The air bag module on my 1993 Coupe was coding a sensor issue and it turned out to be the module itself. These are timing out like the ECU's and about the only place I know of you can send one to get refurbished is here:

Airbag Computer Modules New, Used, Exchanged or Repaired. Airbag Systems, Inc.

Since 1995, Large Inventory of New and Used Airbag Computer Modules. Exchange and Repair Service also availiable

www.airbagsystems.com

 

[jeremyzcook82]

The air bag module on my 1993 Coupe was coding a sensor issue and it turned out to be the module itself. These are timing out like the ECU's and about the only place I know of you can send one to get refurbished is here:

Airbag Computer Modules New, Used, Exchanged or Repaired. Airbag Systems, Inc.

Since 1995, Large Inventory of New and Used Airbag Computer Modules. Exchange and Repair Service also availiable

www.airbagsystems.com

Man I hope it isn’t the module itself. I have to get it inspected before the end of the year. So I am trying to get this fixed. Hopefully once the new sensor is in, the light will go out. It is only throwing a 44 code right now

 

[General karthief]

Have you checked with the inspection station or referee about a temporary registration pending repair?

 

[jeremyzcook82]

Have you checked with the inspection station or referee about a temporary registration pending repair?

Not yet. I ordered a RH crash sensor. If that doesn’t work, or if I get a new code, then I will look into a temp registration.

 

[jeremyzcook82]

Another question is for the VSS. I found when driving the car, the speedometer will read 10 mph faster than what I am actually doing. From what I have researched, the speed sensor on the back of the tranny needs to be replaced. I also notice a check engine light that comes on sporadically/periodically, will stay on for a few seconds and then go off. Could the VSS being off by 10mph cause the check engine light to come on?

 

[Noobz347]

Pull the codes and find out.

Amazon.com

You can also pull them with a paper clip:

Electrical Thread 'How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs'

Jan 27, 2016

@Noobz347 - The code dump procedure isn't in the sticky - you may want to add it...



Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for...

• jrichker
• Replies: 10
• Forum: Fox 5.0 Mustang Tech

• 

 

[AeroCoupe]

VSS is used for cruise control and idle strategy in the ECU. The speedo is mechanical so when they are off that much usually due to a rear end gear ratio change. +/-5 mph is typically a tire size change.

To correct the speedo you need to know the tire size, rear gear ratio, and the speedo drive gear tooth count. The speedo drive gear is the gear on the output shaft of the transmission which on 1993’s is most likely a 8 tooth. Once you know this info you can calculate the number of teeth on the driven gear. This gear is the one on the VSS.

TCI Auto Speedometer Gear Calculator - TCI® Auto

Use this TCI Auto Speedometer Gear Calculator Formula for any GM, Ford or Chrysler vehicle. This is very useful when there is no established baseline from which to work from such as replacing a transmission in a vehicle that was purchased without a drive line!

www.tciauto.com

If you do not know what gears are in the rear end here is how you can figure that out:

Blog | Articles & Videos | Modern Driveline

View the Modern Driveline blog for helpful articles, videos, and DIY resources. We are your trusted source for everything manual transmission conversion.

www.moderndriveline.com

 

[jeremyzcook82]

VSS is used for cruise control and idle strategy in the ECU. The speedo is mechanical so when they are off that much usually due to a rear end gear ratio change. +/-5 mph is typically a tire size change.

To correct the speedo you need to know the tire size, rear gear ratio, and the speedo drive gear tooth count. The speedo drive gear is the gear on the output shaft of the transmission which on 1993’s is most likely a 7 tooth. Once you know this info you can calculate the number of teeth on the driven gear. This gear is the one on the VSS.

TCI Auto Speedometer Gear Calculator - TCI® Auto

Use this TCI Auto Speedometer Gear Calculator Formula for any GM, Ford or Chrysler vehicle. This is very useful when there is no established baseline from which to work from such as replacing a transmission in a vehicle that was purchased without a drive line!

www.tciauto.com

If you do not know what gears are in the rear end here is how you can figure that out:

Blog | Articles & Videos | Modern Driveline

View the Modern Driveline blog for helpful articles, videos, and DIY resources. We are your trusted source for everything manual transmission conversion.

www.moderndriveline.com

The gear ratio and tires are same as what came in the vehicle. No changes there.

 

[Mustang5L5]

The VSS is used for cruise control and for the ECU to know that the car is moving vs stopped. The speedometer is mechanically controlled by a gear. If it’s off by 10mph then the tire size has been changed or the gear is incorrect or something has affected the magnetic head in the speedo affecting its accuracy.


As for the crash sensors…swap them. See if the code goes to the other sensor. If it’s does you know it’s faulty. If it doesn’t, it could be a wiring issue.

Also, the AIrbag module suffers from bad caps like the ECU. At this point I assume all airbag modules need a recap and a new thermal fuse.

 

[jeremyzcook82]

The VSS is used for cruise control and for the ECU to know that the car is moving vs stopped. The speedometer is mechanically controlled by a gear. If it’s off by 10mph then the tire size has been changed or the gear is incorrect or something has affected the magnetic head in the speedo affecting its accuracy.


As for the crash sensors…swap them. See if the code goes to the other sensor. If it’s does you know it’s faulty. If it doesn’t, it could be a wiring issue.

Also, the AIrbag module suffers from bad caps like the ECU. At this point I assume all airbag modules need a recap and a new thermal fuse.

So I checked the tires and they are the standard size that came on them 245/45 R 17 and the rear end is 3.08. I see that they came with a standard 20 tooth gear. I did order a speed sensor but it does not come with the 20 tooth gear. I’ll have to pull mine and see what kinda shape it’s in. Attached is what I ordered for the speed sensor.

 

[Mustang5L5]

Unfortunately that speed sensor will not affect the speedometer at all. The speedo in the dash is mechanically connected to the trans output shaft. So the gear turns the shaft which turns the speedo cable and so on. A new VSS would be needed if you have a code 29 in which case you would have drivability issues as well...mainly stalling at red lights. The VSS is also used for cruise control but a 1993 cobra doesn't have cruise.

I'd likely return the VSS and instead check your current speedo gear and verify it is in fact a 20 tooth. Also, when you remove the current VSS, shine a flashlight into the trans and look at the speedo drive gear color. Yellow would be a 7 tooth and green/white would be 8 tooth.

A 93 cobra would have an 8 tooth drive gear on the trans (if original). Often times when a trans is rebuilt, folks put in a 7 tooth gear. It's also possible the original trans blew up and someone replaced it with a pre-90 T5 that has a 7-tooth drive gear.

Is the odometer accurate? Can you get a GPS app, hit your tripometer and drive 1 mile and see if the odometer and GPS app match up for distance traveled?

 

[jeremyzcook82]

Unfortunately that speed sensor will not affect the speedometer at all. The speedo in the dash is mechanically connected to the trans output shaft. So the gear turns the shaft which turns the speedo cable and so on. A new VSS would be needed if you have a code 29 in which case you would have drivability issues as well...mainly stalling at red lights. The VSS is also used for cruise control but a 1993 cobra doesn't have cruise.

I'd likely return the VSS and instead check your current speedo gear and verify it is in fact a 20 tooth. Also, when you remove the current VSS, shine a flashlight into the trans and look at the speedo drive gear color. Yellow would be a 7 tooth and green/white would be 8 tooth.

A 93 cobra would have an 8 tooth drive gear on the trans (if original). Often times when a trans is rebuilt, folks put in a 7 tooth gear. It's also possible the original trans blew up and someone replaced it with a pre-90 T5 that has a 7-tooth drive gear.

Is the odometer accurate? Can you get a GPS app, hit your tripometer and drive 1 mile and see if the odometer and GPS app match up for distance traveled?

I have the Carfax for Law enforcement login info and I can vouch that the odometer is correct and the mileage is valid. I thought about ordering the black 20 tooth Speedo gear. I’ll have to take the speed sensor off and look in tranny and see what drive gear is in there. I did verify last night the correct tire size and 3.08 rear end is there.

 

[nickyb]

Can you remove the airbag light so you can pass inspection?
My airbag light is blinking since 2020 and it passed smog every year.

 

[jeremyzcook82]

Can you remove the airbag light so you can pass inspection?
My airbag light is blinking since 2020 and it passed smog every year.

That is a great idea. I wonder how thorough they will be though. I know when you put your key in and either place it in the “run” position or start the car, the Airbag light is supposed to initially illuminate. For some reason, GA does this when transferring a rebuilt title from another state to GA. They make you go through the whole rebuilt process.

 

[nickyb]

Ok my title is clean and they let me pull up with it running, I open the hood and they check the tailpipe emmisions.

 

[Mustang5L5]

I have the Carfax for Law enforcement login info and I can vouch that the odometer is correct and the mileage is valid. I thought about ordering the black 20 tooth Speedo gear. I’ll have to take the speed sensor off and look in tranny and see what drive gear is in there. I did verify last night the correct tire size and 3.08 rear end is there.

I meant to verify that a standing mile is in fact a mile.

Get on the highway. Turn your gps app and hit mark and set your trip meter to 0. Drive along and see if 2 miles on the gps does come up at 2 miles on the trim meter. That will help be a clue as to what is off with the speedometer. It’s entirely possible the odometer/tripometer is right and the needle is off due to a change in the magnet strength. The odometer/tripometer is purely mechanical by way of gearing off the speedo cable. So if anything in the speedo gear is not right, it will show up here.

 

[jeremyzcook82]

I meant to verify that a standing mile is in fact a mile.

Get on the highway. Turn your gps app and hit mark and set your trip meter to 0. Drive along and see if 2 miles on the gps does come up at 2 miles on the trim meter. That will help be a clue as to what is off with the speedometer. It’s entirely possible the odometer/tripometer is right and the needle is off due to a change in the magnet strength. The odometer/tripometer is purely mechanical by way of gearing off the speedo cable. So if anything in the speedo gear is not right, it will show up here.

So if the odometer and tripometer is right, but the speedometer needle is off, that means I would have to change out / check the speedometer gear, right?