Lighting Control Relay Problem

[zottic]

I went to start my 1986 Ram 50, the lighting control relay buzzed like crazy. Nothing else electrical functioned. It is an easy swap but my question is, since a new one is very expensive and hard to find, I need to know how to test it or what else could cause the relay to malfunction?

[ragragtimetime]

please elaborate on "Nothing else electrical functioned"...this may be your avenue to explore. relays typically last a long time unless subject to water/moisture & act the way you described when not enough current is passing through them. make sure all grounds are in great shape & use di-electric grease wherever possible...you know check battery ground to cab, frame, engine etc...in the extreme poor grounding situation the clutch cable will become the ground (for a very "short" time) & will snap.

[camoit]

Re check all the battery grounds.

[gnweb]

When my lighting relay started giving me problems, I did not want to spend the $94.00 the part store wanted so I took it apart and cleaned the contacts with emery cloth and haven't had any more problems.

[ahicks66]

I concur with checking grounds and battery leads. Saw a similar issue with my father's '91 Fuso, had a frayed wire grounding out to the chassis but there was enough grease and road gunk to give enough electrical resistance to not pop any fuses. Had turn signals, but hazards and headlamps would cause relays to buzz (resonating between on and off), it would start and run fine, and would occasionally lose memory/clock on the stereo.

I also would check the main feeds if you haven't already. Especially the fusible link box that gets corroded (had this on my '95 MM). Automotive electrical issues are always a headache since completely random and unrelated items will ground out to complete a circuit. Lots of "fun" to troubleshoot.

[pennyman1]

also check the back of the fuse box for issues - the windshield on these trucks will leak and run right down the back of the panel and cause all sorts of problems - the lighting relay is there too.

[htsmeister]

Hi gnweb, did you get your problem figured out? I had this problem a long time ago and it turned out to be the fusible link down by the alternator was blown. I replaced it and everything worked great. Now I am having the same problem again and the fusible link is fine. The switch appears to be ok. Tomorrow I will try cleaning the relay contacts with emory cloth and checking all the system grounds. Did you find the replacement part number for the relay?

[gnweb]

I polished up the contacts in the lighting relay with some real fine emery cloth and so far they have been working fine (knock on wood) I saw 1 parts store that was showing a listing that was over a $100.00 but they did not stock it.