The glow plug relay on my diesel Mercedes, an 83 300SD has two sets of parallel contacts but only uses one because the other has a gap of about
0.035" when the first set closes. I thought this was due to improper alignment and I bent the other arm so that both would make contact. The other day I found another relay and noticed that it had one set of contacts spaced so they didn't close. Are there any experts out there that can tell why they do this? My guess is that the open set is a spare for when the first set wears too much. But that doesn't make sense because two sets working in parallel wouldn't wear as fast. Also would like to know if anyone has reversed engineered the circuit as it has an IC and a couple transistors. The circuit acts as monitor to make sure glow plug no. one is drawing current and then turns a dash light indicating that the plugs are heating and when it goes out in a few seconds it OK to hit the starter. tnx- posted
19 years ago