locating P.C. board

[teigan]

i'm trying to find the printed circuit board for the engine fan timer. i looked in the ignition box of my '84 and only found a box labeled ignition amplifier. is that where the circuit board is, and if so, how does it open? undoing the bolts has no affect.

[teigan]

nevermind. i got impatient, and traced the wires myself. thanks anyway.

[lotusguy]

Hi,

As you've probably found out, the engine bay cooling fan timer is mounted on the ignition box cover interior.

The connector to the PC board is pretty poor and is often the source of the failure.

Be mindful that there is also a relay for this unit as well as the 'kill' switch and a thermostat located inside the engine bay cover itself. This bi-metal 'T'stat is also prone to failure. Cleaning the contacts with some emery paper and adjusting (bending) the contact arm will correct it. I have used a Bic lighter held at a distance under it to check the adjustment (with the unit removed of course). Hope this helps.
Happy Motoring! ...Jim'85TE

[teigan]

thanks again jim. you always seems to be be there with a rescue. the thermal sensor is healthy. my problem is the relay is stuck closed and constantly leaking power from the battery. i removed the relay and my battery problems stopped. so i removed the timer circuit and analysed the circuit. there are two flaws to the design: 1) a capacitor chosen as a power filter is too big, giving zero filtering. 2) the boolean logic used via an inverter IC is circular, meaning the IC will busily calculate itself to an early demise. and that is what happened on my board. for now i'm replacing the one damaged chip, but it will eventually fail again. the 2 chips the desisner employs is a boolean counter and a sixtupled inverter. there are far better and easier ways to make a 15 minute countdown timer. does anyone have facilities to photoetch some printed circuits for everyone? i can easily design a new circuit and send you the layout picture to photostat. new parts would be less than $25.