Anybody know where the speed signal wire is on an 04.5? I'm putting in a pioneer gps unit and it has to be hooked into the speed signal wire and i cant find a wiring diagram any where.

 

I believe the speed sensor for our trucks is on the top inside of the rear diff axle housing. I can get the wiring diagram tonight when I get home. I think it is connected on a brakeline mounting bracket IIRC. Has a wiring harness connected to it.

 

Where you tap will depend on whether they want the signal modified by the ABS or not modified. I would assume modified but might want to check that.

 

it just says connect to the speed detection circuit, the manual calls it a speed pluse wire. So im assuming just the wire that runs in speedo gauge on the instrument pannel

 

That might be a little harder to do. Computerized and intergrated at the instrument cluster.

The speedometer gives an indication to the vehicle operator of the vehicle road speed. This gauge is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus. The speedometer is an air core magnetic unit that receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (run-start)
circuit whenever the ignition switch is in the On or Start positions. The cluster is programmed to move the gauge needle back to the low end of the scale after the ignition switch is turned to the Off position.

 

The ecm has to have a pluse wire tied into it some where though and i'm thinking thats what i'm looking for. I know on jeeps they have a toner ring in the transfer case/transmission that generates the pulses for the ecm to read, guess i'm going to have to call pioneer to see exactly what they're looking for here

 

That is the sensor that I referred to above mounted on the rear diff case. That is the sensor that the ecm reads and coverts to speed.

 

ECM reads output from the ABS module not the diff sensor. There is quite likely a difference in the signal. Should be able to source the wire coming out of the ABS module. The 03 FSM and the 05 FSM both show the speed sense wire as pin #12 on the ABS module with a color code of DG\YL. Should be the same color on the 04's.

Just so there is no confusion, the 04.5 trucks don't have a PCM. The signal runs from the ABS module to the ECU then is outputted again to the cluster module to set the speedo.

 

What pin # and color is the wire comming from the ecu to the cluster?

 

OPERATION
The speedometer gives an indication to the vehicle operator of the relative vehicle road speed. This gauge is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus.

The speedometer is an air core magnetic unit that receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (run-start) circuit whenever the ignition switch is in the On or Start positions. The cluster is programmed to move the gauge needle back to the low end of the scale after the ignition switch is turned to the Off position. The instrument cluster circuitry controls the gauge needle position and provides the following features:

Vehicle Speed Message - Each time the cluster receives a vehicle speed message from the PCM it will calculate the correct vehicle speed reading and position the gauge needle at that relative speed position on the gauge scale. The cluster will receive a new vehicle speed message and reposition the gauge pointer accordingly about every 88 milliseconds. The gauge needle will continually be positioned at the relative vehicle speed position on the gauge scale until the vehicle stops moving, or until the ignition switch is turned to the Off position, whichever occurs first.
Communication Error - If the cluster fails to receive a speedometer message, it will hold the gauge needle at the last indication for about ten seconds, or until the ignition switch is turned to the Off position, whichever occurs first. After ten seconds, the gauge needle will return to the left end of the gauge scale.
Actuator Test - Each time the cluster is put through the actuator test, the speedometer needle will be swept to several calibration points on the gauge scale in a prescribed sequence in order to confirm the functionality of the gauge and the cluster control circuitry.
The PCM continually monitors the vehicle speed sensor or the Controller Anti-lock Brake (CAB) to determine the vehicle road speed. The PCM then sends the proper vehicle speed messages to the instrument cluster. For further diagnosis of the speedometer or the instrument cluster circuitry that controls the gauge, (Refer to 8 - ELECTRICAL/INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING).

For proper diagnosis of the vehicle speed sensor, the CAB, the PCM, the PCI data bus, or the electronic message inputs to the instrument cluster that control the speedometer, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

 

Myself, I would take the reading straight from the diff sensor, and adjust the GPS unit accordingly. You can't get the info straight from the ecm because it is transmitted on the bus along with tons of other info. You could tap into it , like said before, from the abs module, but you don't know the modifications made to the signal for the ecm then........

 

You can't tap the signal from the ECU to the cluster, its wrapped in a jumble of other things. Most units that need a speed signal are tapping the speed sense wire between the ABS module and the ECU. Thats what makes me think the signal is not correct before the ABS and after the ECU, or it could just be a convenient spot.

As near as I can tell the DG\YL wire should be pin #22 on the ECU B connector.

 

well on my 04 i spliced a switch to a wire under the fusebox under the hood,when i flip the switch it shuts down the speedo to get rid of the speed limiter,i think it was orange with a white stripe on mine,urs probaly dif,but thats a good place to start from,someone should have a wiring diagram for ur 04.5 and tellu what color wire under the fuse box,i removed the 2 bolts and pulled her up and out of the way to get acsess to the wire,im sure that will work for u as its directly related to the speedo,hope this helps