Operating Instructions - Snap-on Equipment

General MaintenanceConnecting To The Vehicle1. If you are obtaining RPM from a high voltage spark plug wire, place theprobe around any plug wire and close the probe.✓ If RPM cannot be obtained, move the RPM probe to a differentplug wire OR reverse the direction of pickup probe on the plugwire.2. If you are obtaining RPM from the low voltage ignition coil primaryconnections, with proper configuration as described above, place theinductive pickup around the low voltage wire going to the ignition coil.✓ Other vehicle components, such as fuel injectors or battery feedwires for coil on plug systems may also produce a signalequivalent to the engine speed. The inductive probe should NOTbe placed around two wires at any time, a single battery feed +12Vis the correct wire.RFI, Radio Frequency Probe (Non-contact)Follow the setup instructions for the Inductive probe (Using The Inductive Probe,page 4-4) except for Ignition Connection select Non-Contact. All other steps listedfor the inductive probe apply.Connecting to the Vehicle1. If not done already connect the RFI (Non-Contact) RPM probe into theyellow RPM extension cable in place of the inductive probe.2. Attach the battery clamp of the RFI probe to a CLEAN solid engine groundpoint. You can use the battery NEGATIVE cable if it is clean or any othersolid engine metal connection point.3. Position the cable of the RFI probe ONLY, not the yellow cable, over theengine and spark plug wires. The cable can be simply laid out over theengine; it is not necessary to wind the cable around the wires. The cableshould be positioned as close to the ignition coil as possible.✓ Make sure the cable does not come in contact with any moving engineparts such as pulleys or belts. Also make sure the cable does not contactany part that will become excessively HOT such as an exhaust manifold.If the RPM signal is erratic or seems incorrect, reposition the cable, insure a goodground and try again. Because the principle of the pickup is to sense ignition noiseand convert it to an RPM signal, some ignition system designs may make it verydifficult. If problems continue to be experienced, use a different engine speedmeasurement device.OBD RPM PickupFollow the setup instructions for the Inductive probe (Using The Inductive Probe,page 4-4) except for Ignition Connection select OBD. All other steps listed for theinductive probe apply.The OBD RPM device is designed to be used on 1996 and newer vehicles ONLY.These vehicles are equipped with the OBD II Emissions system. See Appendix Aof this manual for additional information and vehicle connector information ifunfamiliar with OBD Systems.4-6