Speedometer doesn’t work 4.6 swapped

Petericaza · Dec 11, 2019

my speedometer doesn’t work but every other gauge does on my 99gt cluster my car was a 2004 v6 swapped with a 99gt everything I don’t know how to fix this speedometer problem my obd2 read the car is going 17 kph max even when we are on the highway

tsemmett · Dec 12, 2019

Have you checked the speed sensor as 08GT500 suggested? The fact that OBD doesn't have the speed means the ECU doesn't either.

Sluggie24 · Dec 12, 2019

Is it an automatic trans? If so 99-03 read vehicle speed differently than 04 did due to a change in the transmission.

Petericaza · Dec 12, 2019

Sluggie24 said:
Is it an automatic trans? If so 99-03 read vehicle speed differently than 04 did due to a change in the transmission.

It’s a 1999 engine v8 in a 2004 body the obd was reading speed but the actually speedometer was not moving

Petericaza · Dec 12, 2019

tsemmett said:
Have you checked the speed sensor as 08GT500 suggested? The fact that OBD doesn't have the speed means the ECU doesn't either.

The obd does have speed actually but the speedometer was not moving at all

tsemmett · Dec 12, 2019

You said "my obd2 read the car is going 17 kph max even when we are on the highway", which is about 10 MPH, the lowest reading on the speedo.

Did I misread that, and OBD is showing the correct speed? If this is the case, check the sending unit on the transmission.

Petericaza · Dec 12, 2019

Oh I would think there would be a little bit of movement. Where would the speed sensor be is it on the drivers side of the transmission?

tsemmett · Dec 12, 2019

It may be that the speedo should move, but that is also right at the bottom of the speedo (mine starts at 10mph), and they aren't 100% accurate. Could be that it's just low enough not to actually show on the speedo.

In any event, the PCM controls the speedo; if it thinks you're only doing 17 kph at highway speeds, something between it and the speed sensor is off.

I do believe the speed sensor is on the driver's side, but it should be the only electrical connection on the tail of the trans; on my T45. You might confirm it's even the right type (if the trans is 98 or older it wouldn't be for instance).

Petericaza · Dec 12, 2019

I’m not sure what trans I have that’s the problem I know the 98 and older have some type of cable

tsemmett said:
It may be that the speedo should move, but that is also right at the bottom of the speedo (mine starts at 10mph), and they aren't 100% accurate. Could be that it's just low enough not to actually show on the speedo.

In any event, the PCM controls the speedo; if it thinks you're only doing 17 kph at highway speeds, something between it and the speed sensor is off.

I do believe the speed sensor is on the driver's side, but it should be the only electrical connection on the tail of the trans; on my T45. You might confirm it's even the right type (if the trans is 98 or older it wouldn't be for instance).

right I will check that is that is there any reals ya to tell if it’s the sensor or a wiring issue or do I just replace it

tsemmett · Dec 12, 2019

The 96-98s still have an electronic sending unit, the difference is it's driven by a gear in the transmission, where the newer ones uses hall effect sensor/toothed wheel.

I'd probably ID The trans first; there should be a metal tag on the transmission with the model and part numbers. Check this for more: Identify Transmission Code

Petericaza · Dec 12, 2019

tsemmett said:
The 96-98s still have an electronic sending unit, the difference is it's driven by a gear in the transmission, where the newer ones uses hall effect sensor/toothed wheel.

I'd probably ID The trans first; there should be a metal tag on the transmission with the model and part numbers. Check this for more: Identify Transmission Code

If I have a 96-98 transmission would I have to get a 96-98 gauge cluster and have it reflashed ? Or...

tsemmett · Dec 12, 2019

A 96-98 cluster is not PCM controlled, so it's not quite that simple. Find out what tranny you have first and let's go from there; it could be something much simpler.

Petericaza · Dec 12, 2019

Alright after school today I’ll go check it out. Thanks for the help so far been very useful

Petericaza · Dec 12, 2019

I could not find the tag for the transmission however I did the next best thing a visual inspection and it looks like it’s a t45 transmission down there

wmburns · Dec 12, 2019

For the 1999-2004 model year the output of the transmission OSS speed sensor goes directly to the PCM and only the PCM. The PCM de-codes the speed and the TELLS the cluster what speed to display via SCP data packets.

Soooooooooooooo if you want to trouble shoot this, the process begins with finding out IF the PCM "knows" the correct speed.

IF the PCM has an incorrect speed THEN the problem is between the OSS sensor and the PCM or in the PCM programming.

Otherwise the problem is in the cluster itself or in the data communication between the PCM and the cluster. OBTW, if the cluster displays the correct mileage and the rest of the cluster works, IMO it's reasonable to assume that the cluster to PCM data packets are working.

Here's some information on how to trouble shoot and/or repair a cluster. However, I recommend having the cluster professionally repaired if needed. The fee is not really that high and the guys that do this sort of work on a regular basis will be more accurate. I have had great luck using united speedometer and electrical.

My odometer goes on and off?

My odometer goes on and off?

I've notice that my odometer on my '02 mustang has been going on and off at anytime. I started to see this when my car reached 90K. I also have a '99 F-150 that stared when it reached 90K also now has 102k. Has anyone else had this problem with any mustangs out there?:headscratch:

www.allfordmustangs.com

Here's also a case where a powerful ODB2 scanner with bi-directional capabilities can provide a ton of useful information. The ODB2 below can also talk directly to the cluster to "learn" what the cluster believes it's view of the world is.

ForScan ODB2 scanner w ELM327 USB

ForScan ODB2 scanner w ELM327 USB

While working on your car have you ever wanted: to find an ODB2 operational PID value (say fuel pressure or MAF)? How about graph a PID value over time? Or compare multiple PID's over time? Access a bi-directional PCM control such as test a...

www.stangnet.com

NOTE2. Mustangs older than 1999 use a VSS style transmission sender. The VSS sensor output is NOT compatible to an OSS sensor. The signal is different. The wiring to a VSS sensor is also different. If someone has mixed/matched parts from a 1998 and older Mustang with a 1999 Plus Mustang this could explain some of the problems. The type of speed sensor used in your application is easy to see. A VSS sensor is driven via a worm gear. Where as an OSS is a non contact sensor similar to the ABS tone ring.

wmburns · Dec 15, 2019

Re-post of information in another thread to keep all of the speedometer related trouble shooting together.

As stated in other posts, IF the speed is incorrect at the PCM, THEN it will be incorrect at the cluster. Since the PCM speed is obviously wrong, the focus should switch to:

The transmission speed sensor
the wiring between the speed sensor and the PCM

I have answered tons of posts over the years from people that have mixed/match various parts from different model years "assuming" that all Mustangs are the same (it bolts up fine so it must be OK). One of the frequent threads that come up is when someone swaps a transmission with a VSS sensor into an application that is expecting an OSS sensor.

The T45 does support both an OSS sensor or VSS sensor depending upon which tail shaft was used. You need to find out WHICH speed sensor you have. IMO one way to do this is by removing the speed sensor and looking down into the hole. IF you see a worm gear, then the sensor is a VSS style. If you see reluctor wheel teeth, then it's an OSS style. Here's is some more information to help you to understand the difference.

T-45 Tail Shaft Swap
T-45 Tail Shaft Swap - Ford Mustang Forum
T-45 Tail Shaft Swap 4.6L Tech
www.allfordmustangs.com

The next set of trouble shooting depends upon WHICH sensor is in the transmission.

Petericaza · Dec 15, 2019

You may be on to something hopped under the car and saw this.. not sure if it’s vss or oss but here take a look

wmburns · Dec 15, 2019

Best to remove the sensor and LOOK down the hole....

Petericaza · Dec 15, 2019

Ah Ight I’ll do that tommorow I guess just lowered my car an hour ago

Petericaza · Dec 16, 2019

Alright done that today not sure if it’s a worm gear or not but here ya go also found the Tranny tag

Speedometer doesn’t work 4.6 swapped

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