OBD1 S52 wiring issues

[mcdougal]

This pertains to an S52 converted to OBD1 that has been swapped in my 86 ETA. Had a forum member come over to do the wiring today and the car runs and drives which is great. The problem is that the tach doesn't work and the heater fan doesn't turn on. The tach has jumped up to 1k rpms a couple times right when I start it but then it goes down to zero and doesn't move. We checked continuity for the tach signal between the gauge cluster and the c104 pin (good), and between the c104 pin and the c101 (good). The speedo works on the stock eta cluster and an "i" cluster I have but the tach doesn't work in either.

Any ideas on the tach? Also, any reason you can think of that my heater fan isn't working now but it was before?


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[netcsk]

Can't comment on the tach.
On the heater fan, do your windows, sunroof, and interior lights work? If no, it's probably related to your unloader relay which is tied into the starter. It should be a black/yellow wire that connects to a terminal on the starter. The starter grounds the relay except when starting, where it applies 12V to deenergize the relay to prevent high load stuff from operating while starting the car.
If you have the etm, check page 1240-1.

[mcdougal]

OBD1 S52 wiring issues

Can't comment on the tach.
On the heater fan, do your windows, sunroof, and interior lights work? If no, it's probably related to your unloader relay which is tied into the starter. It should be a black/yellow wire that connects to a terminal on the starter. The starter grounds the relay except when starting, where it applies 12V to deenergize the relay to prevent high load stuff from operating while starting the car.
If you have the etm, check page 1240-1.

The windows and interior lights are working. There is a black/yellow wire on the small bolt of the starter. Should this wire be grounded or am I misunderstanding its purpose?


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[mcdougal]

It ended up being a blown fuse (#20 I believe). Put a new one in an the fuel gauge, temp gauge, tach, and heater fan all work. She's purring like a kitten.

https://vimeo.com/122257342

https://vimeo.com/122257385

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[mcdougal]

The heater stopped working again but everything else is still work fine. Weird...


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[mpowerful]

My guess is your blower motor or the resistor is crap. Does it work on fn speed 4.