No Speedometer and intermittent tach after Swap

[divemaster5734]

Put a fresh reseal on a low mileage 7.3 and the zf it came with into my previously E4OD with blown engine.
The speedo doesn't work.
I used the cable, transmission harness, and the dash from the donor to eliminate the PRNDL and the extra wire for the auto.
I have no information on the previous operation of the donor as the previous owner passed away, and the truck sold as scrap in an estate sale.
That said, I wasn't sure about where to set the spinning interior when inserting it back into the zf.
I assumed that when the speedo cable was fastened down the cable play would sort itself out.
I did notice that there was no resistance when installing in the relocated dash, I was able to spin, pull out, or push in at will, and honestly, didn't have much confidence it was going to work.
The tachometer worked intermittently at first, but only register around 2k rpm or higher, then it would indicate down to about 1k before dropping.
That lasted for about a total of an hour of run time, a few short idles to check and fix nuisance leaks, and a 25 minute idle to get oil circulated everywhere it's going to go inside to confirm the level.
Hoping for speedo install tips, and didn't know if there was a way to test the sensor before dropping $75 for a new one.
Thanks

 

[WMO4IDI]

Your tach is a simple wiring issue. Check the connector on the sensor & behind the instrument cluster. Sometimes the 3 prongs from the tachometer clipping into the cluster can have a bad connection as well. I just rewired mine directly from the cluster connector to the sensor. Sensor has direct ground & the other is signal ground to cluster. The tach also uses a +12v & a 2nd ground from the cluster connector.

As for the speedo, if it's a 2wd & you remove the yolk, you should see the plastic gear inside the tranny. It has to click in behind the cluster, it can be a pia to line up the metal shaft as it doesn't stay straight in the connector, the tip can touch the edges and refuse to engage. I recommend disconnecting from the tranny & pulling the cable out enough so you're not fighting it.

 

[divemaster5734]

Your tach is a simple wiring issue. Check the connector on the sensor & behind the instrument cluster. Sometimes the 3 prongs from the tachometer clipping into the cluster can have a bad connection as well. I just rewired mine directly from the cluster connector to the sensor. Sensor has direct ground & the other is signal ground to cluster. The tach also uses a +12v & a 2nd ground from the cluster connector.

As for the speedo, if it's a 2wd & you remove the yolk, you should see the plastic gear inside the tranny. It has to click in behind the cluster, it can be a pia to line up the metal shaft as it doesn't stay straight in the connector, the tip can touch the edges and refuse to engage. I recommend disconnecting from the tranny & pulling the cable out enough so you're not fighting it.

Thanks

 

[nelstomlinson]

We're going to need to know what years the base truck and donor were.

 

[divemaster5734]

We're going to need to know what years the base truck and donor were.

Base truck - 1989 F350 XLT Lariat Crew cab, short box, E4OD, Centurion (4 door Bronco) Conversion
Donor truck 1990 F350 XLT Crew Cab, long box, Zf542.
Converted to ZF.

 

[nelstomlinson]

Oh, good a simple mechanical speedometer, not the electronic nightmare I'm fighting on my '94.