Every month we receive a substantial number of technical questions, many of which deal with electrical problems. Recently we were in Texas visiting the folks at Painless Performance and had the opportunity to eavesdrop on Joe Armstrong, a member of their tech support team. Joe handles a huge volume of calls on a daily basis and he always has the answers customers are looking for. As we talked with Joe, we realized many of the questions he deals with are similar to those we are asked. Unfortunately, we seldom have the space in the magazine to publish all the queries that come our way. So, thanks to Joe, we've decided to dedicate this month's column to some of the most common electrical problems.
Q.I am installing a universal chassis harness and none of my accessories have power with the key on. What should I look for?
A.Older OEM ignition switches only have terminals for four circuits-battery, accessory, ignition, and start. Today's universal harnesses can have up to six circuits for the ignition switch-two battery, accessory, ignition accessory, ignition, and start. The two battery circuit leads of the harness can be placed on the battery terminal of the switch, accessory wire to the accessory terminal, ignition wire to the ignition terminal, and the start wire to the start terminal. This leaves ignition accessory wire. This is the circuit used to power accessory devices only used with the key in the run position-devices such as an electric fuel pump, turn signals, wipers, HVAC, gauges, and electric cooling fan. The ignition accessory circuit should be connected to the same terminal as the ignition. This will provide power to these circuits with the key in the run and start positions, leaving the accessory terminal for radio operation only. This way you can power the radio in the accessory position of the ignition switch without draining excessive battery power.
Q.I do not have spark after installing an HEI system. Do I need to rewire the ignition switch to make it work?
A.Most vehicles using a coil have a resistor in the power circuit. For starting purposes, the ignition system had a bypass to supply more voltage to the coil for faster startup. The bypass is a secondary circuit that may be supplied from a second ignition terminal on the ignition switch or from the starter solenoid. Since the ignition system was supplied power from the bypass, the ignition terminal on the switch lost power in the start position. To overcome this, a circuit is required from HEI power circuit to the bypass circuit. The bypass circuit will come from a terminal on the solenoid or ignition switch, which only has output power in the start position.
Q.My cooling fan does not come on after installing a thermostatic temperature switch, but it will work in manual mode. It seems simple, but can the sender be installed incorrectly?
A.Since this is installed into a water jacket, some installers will install Teflon tape to the threads of the thermostatic switch to prevent a coolant leak. The threads on the thermostatic switch provide a path to ground, which is used to trigger the cooling fan relay at operating temperature. Teflon creates a barrier between the threads and the ground supplied through the engine block.