Some BJ40 electrical questions.

[Belgique Basterd]

I started doing the electrical on my truck, but the old wiring harness is too damaged by the previous owner that it would be stupid putting it back into my truck.

So I am planning to take the stock wiring harness apart and only use the thick wires since they are ok (starter, glow plugs,...)

I've been having some trouble with my glow plug relay (sometimes 24 volt output, sometimes 7 volt, sometimes no volt) I was thinking to swap this out with a regular aftermarket relay, but I have no idea how many amps this should be, anyone got an idea?

Next problem is fusible links, there are none in the harness right now, and I would like them back for security in case of a major electrical problem. My plan is to put in Maxi fuses in the harness instead of fusible links, but again I do not know the amps of the fusble links, anyone got an idea?

For the smaller stuff (lighting, heating, windshield wipers,...) I'm planning on using relays too, now can 12 v relays be used in a 24 volt system (12v are easily be found here and are dirt cheap)?

Thanks for your time!

 

[cruiser_guy]

The glow plug relay, depending on year and model, may be OK. The superglow system works something like that.

I would NOT use 12v relays in a 24v system. You WILL burn them out. Check for 24v relays at heavy equipment suppliers. Most heavy equipment is 24v.

 

[Belgique Basterd]

The glow plug relay, depending on year and model, may be OK. The superglow system works something like that.

I would NOT use 12v relays in a 24v system. You WILL burn them out. Check for 24v relays at heavy equipment suppliers. Most heavy equipment is 24v.

I have heard this from other people too, but I've been having problems with starting the engine when it's cold. If I hotwire the glowplugs (wire from
+ terminal on battery to the glow plugs) the engine starts perfectly. So I figure if I use an aftermarket relay this would solve my problem. All I need to know is how many amps the relay should be.

 

[Stone]

Hella should be readily available in Europe. The part number for their 24v relay with an inline resistor on the coil is #87426. The resistor prevents large voltage spikes in the electrical system as the coil flips on and off. If you needa 24v relay that is weatherproof for installs under the hood, then the part number for that is #87421 and the matching weatherproof base is #87173.

Relays have a relatively small current capacity. Hella's 24v relay capacities are 10A on the coil side (switch) and 20A on the load side. This will work great for most accessories including two large auxilliary lights, but will be nowhere near what you need for the glow system...unless you're just using the relay as a switch. To carry the load of the glow system you will need a heavy duty 24v solenoid. Even the heaviest duty 24v relay that Hella makes (SPST) only takes a maximum of 50A on the load side...the part number for that is #87113. Cheers.

 

[Belgique Basterd]

Thanks for the reply, but what is the difference between a relay and a solenoid, I tought the solenoid was the magnetthingy in the starter that shoots forward when current is applied to it?

 

[Stone]

Oops...sorry, I used the wrong term. I didn't mean solenoid. What I meant was the huge heavy duty glow relay that's normally found inside the engine compartment which is designed to take large loads, and is malfunctioning in your case as you indicated. I don't know a supplier of these. I don't think that you can replace this with a regular relay, unless you maybe split the four glow plugs into two banks of two and use two heavy duty 24v relays?

 

[Belgique Basterd]

Ok, thanks, so anyone has any idea how much current the glow plugs draw? I have the multimeter thingy at home, how do I set it up to measure the amperage when current is fowing to the glow plug?

 

[denis]

I'd take a guess at 25A or something
Make sure your multimeter is rated OK for 50A at least, if it's OK, plug it into the circuit in series.
electricity is a PITA sometimes... Good luck

 

[Stone]

I did a little bit of searching, and originally I thought a "solenoid" was a specific term meaning a device that turns electricity into mechanical force. So in a relay, the solenoid portion is the coil that produces a magnetic field flipping the switch inside the relay to control current flow.

Apparently, a "solenoid" can also mean "Relays that remotely switch high currents." Cole Hersee has a site that gives specifications to the many solenoids that they produce...many of the able to switch several hundred amps of current. I think if you can find similar products in Europe, these are you best bets to switching high current demand applications like your glow system. I apologize for the confusion, I was foggy on the terminology myself.

http://www.colehersee.com/catalog_top/index.htm