Ignition relay help needed

[guy99]

Hola from Sonora Mexico.

While traveling from Puerto Penasco (Rocky Point) to Bahia Kino (Kino Bay) yesterday we experienced a total ignition failure. With luck we were able to coast to a dirt road and get off the highway. (A good thing since there was only one lane in our direction and NO shoulder). After a bit of poking around found that with the key in the on position there was no power to the distributor, or electric fuel pump, or anything else powered when the key is on. With the help of some very nice people haywired power to the ignition et al at the fuse panel. Drove to RV Park in Santa Ana, this morning the proprietor brought a mechanic who determined that the ignition relay had failed. Off he and the RV Park owner went to get a replacement. After some considerable while they returned and reported that they had been unable to find the needed part new, but had obtained one from a junk yard. Installed the part and all is good, but for how long?

We will be passing through Hermisillo tomorrow and MAY be able to get a new one. As an alternative, is there is any reason why I shouldn't reverse engineer the wires coming in to the relay and replace it with a more modern relay such as this:

[eubank]

They crap out from time to time. Make sure they don't get wet (with whatever); it can cause corrosion inside and failure.

Lynn

[TBSarfari28]

Guy99,
The Bosch relay you show can handle 20amps on the NO normally open contacts, that's between terminals 30 and 87. 30 amps on the NC normally closed contacts, that's between terminals 30 and 87a. If the total current load of the circuits supplied by the old relay are within the amp ratings I have listed, you would have no problem. Can you take a photo of the old relay? and post. I would like to see what type you are trying to replace. You stated that you were in a RV park in Santa Ana? is that CA.

[Excella CM]

In a pinch you can simply jump the socket from the blade that is orthogonal to the others to the second one irectly in line (the top and bottom ones in your photo. You need to undo the jump when you shut down.

[guy99]

Originally Posted by TBSarfari28

Guy99,
The Bosch relay you show can handle 20amps on the NO normally open contacts, that's between terminals 30 and 87. 30 amps on the NC normally closed contacts, that's between terminals 30 and 87a. If the total current load of the circuits supplied by the old relay are within the amp ratings I have listed, you would have no problem. Can you take a photo of the old relay? and post. I would like to see what type you are trying to replace. You stated that you were in a RV park in Santa Ana? is that CA.

Santa Ana, Sonoma, Mexico. Santa Ana Sonora Mexico Driving Map


I would need to use the NO terminals. I'm not sure I can tell what the max current on the circuit would be. I suppose I could stick a 20 amp fuse in the circuit.

I'll post a picture of the old relay when I can.

[guy99]

Here are the picture of the connector and the relay.
The connector:

Terminals on the relay:

Side of relay:

Other side of relay

[TBSarfari28]

The Bosch relay would most likey handle the current load of the circuits. If the current is over 20 amps the contacts would handle the load for sometime, til you get home or state side. If you can fine a parts supplier in the area that has truck parts, you could get a Cole Hersee solenoid part number 24059, this would more than handle the current, would out last the motorhome. Go to Cole Hersee Co. then click on solenoids, the first photo on the left is the type. It must be mounted vertically, and could be installed in the same area as the old one. They are used on many heavy-duty trucks as accessory relays. The two small terminals are the coil, and the load circuit the large terminals. Hope this helps. Good luck!

[overlander63]

That was a standard relay for some years. When you get back to the states, you should be able to get a replacement for it, along with a spare. If the mechanic making the field repair hasn't done so, he can use male spade connectors to wires, to female spade connectors, to the Bosch relay. That way, when you get home, all you have to do is unplug the male connectors, along with the relay.

[guy99]

Thanks fellows.

I'm going to try to make it to Kino Bay on the junk yard relay. From there I will take the toad in to Hermosillo to look for the proper part (or a better substitute ala TBSafari28).

If I have another failure or can't find a suitable part, I'll do as Terry suggests (good idea with the wires).

An interesting thing about the Bosch relay is that it has a schematic embossed in the side of the case.

Do you happen to know the pin assignment on my existing relay?

[TBSarfari28]

My real background is in heavy-duty vehicles, and the old relay is not a common one used in my area of experience. I have seen them, I believe the two terminals in the middle that are closest together are the coil. On your Bosch relay that would be terminals 85 and 86, it does not matter which way you hook the wires up, 85-86 or 86-85 from the old relay. The other two would be the load circuit, connect the two wires from the old relay to terminals 30 and 87 of the Bosch relay, again it does not matter which wire goes on what termnal. Usually the hot side coming from the battery/fuse side connects to terminal 30 and load circuits to terminal 87. Take the old relay and have someone check to see what is wrong with it, open in the coil or hgih resistance in the NO contacts. It most likely just died of old age. If the NO contacts have burned because of higher than normal current draw, caused by a fuel pump that is starting to fail or some other load/component in the circuit that is drawing to much current the new relay with fail soon. Take a spare with you, just in case. Hope your trip has no other problems.

[bkahler]

Originally Posted by TBSarfari28

.....If the NO contacts have burned because of higher than normal current draw, caused by a fuel pump that is starting to fail or some other load/component in the circuit that is drawing to much current the new relay with fail soon. Take a spare with you, just in case. Hope your trip has no other problems.

You bring up an interesting point about the fuel pump. Its my understanding Airstream added an electric fuel pump to the classic motorhomes after reports of vapor lock were reported. I wonder if the addition of this fuel pump might be overloading the relay. This is just speculation but we all might expect to see these relays start to fail in the years to come.

After reading these posts I'm considering adding a separate relay just for the electric fuel pump. Also carrying a spare relay is good practical advice that I plan on following.

Thanks

Brad

[overlander63]

Originally Posted by bkahler

After reading these posts I'm considering adding a separate relay just for the electric fuel pump. Also carrying a spare relay is good practical advice that I plan on following.

Brad, your MoHo should already have a separate relay for the fuel pump, especially if it is fuel injected.

[bkahler]

Originally Posted by overlander63

Brad, your MoHo should already have a separate relay for the fuel pump, especially if it is fuel injected.

Terry, unfortunately our 84 310 is not fuel injected. When I get a chance I'll chase down the wiring for the fuel pump and see if it has its own relay. If it does then I need to make sure I have a spare for it as well as the ignition relay.

Thanks!

Brad

[guy99]

OK, I'm confused.

Started out today headed for Kino Bay. Rig began to stumble under constant load (65 MPH) and have poor/no power for acceleration.

Found a spot to pull off. Shut down. Tried to restart, wouldn't start. Found no power to distributor with key on. So I figured it was the problem relay. Assuming that the relay was simple and that I could jumper around its function, I jumped between the input (always hot) and the output. As soon as I did, the starter ran but rig would not start. I was surprised since I though this was the ignition relay not the starter relay. Must be a starter relay, but why when it was failing would they starter still run off of the key? Ran a wire with a switch from hot to ignition primary. Flip switch, turn key to start, starter engages, engine starts, we are good to go.

OK, this relay must be the starter relay, why is the ignition primary dead?

[TBSarfari28]

Possible bad ignition switch. Check for power to ignition primary in the run position and start postion, wiggle the key/ignition switch as you check for power. If the power is intermittent, you have a bad/worn ignition switch, old age. I would not use the Bosch relay you had in the above picture for the starter relay, the cureent draw of the starter solenoid windings both pull-in and hold-in windings are close to 20amps. Get a new relay like the original or the Cole Hersee above. Good Luck again.

[overlander63]

Possible bad ignition switch, or fusible link at the starteer solenoid (lots of fun to check). If your rig has no fuel injection, and no ecm, you can hot wire it so you can get out of there by hooking a wire directly from the battery + to the batt connection on the distributo cap.

[guy99]

Quick question, should the ignition primary (which by the way has the power to the fuel pump directly attached) be supplied via a relay?

If so, any ideas of what it would look like / where it would be located?

The wiring in my rig is a real butch job and certainly not stock but a starting point might help me sort it out.

I'm pretty sure it's not the ignition switch since no amount of wiggling gets any power to the distributor, no power in the start position, and SOME accessories get power when I turn the key to the ON position. I'll still check.

[TBSarfari28]

The fuel pump could use a relay much like the starter relay. What brand of chassis is your motorhome built on? I maybe able to get some info to answer your questions, if I know the chassis brand. If you have no power to the distributor during cranking the unit won't start, I am confused, you must have a real wiring mess. You may need to get a wiring diagram for the chassis and start tracing each circuit on the unit and see what has been done to mess it up.

[guy99]

Originally Posted by TBSarfari28

The fuel pump could use a relay much like the starter relay. What brand of chassis is your motorhome built on? I maybe able to get some info to answer your questions, if I know the chassis brand. If you have no power to the distributor during cranking the unit won't start, I am confused, you must have a real wiring mess. You may need to get a wiring diagram for the chassis and start tracing each circuit on the unit and see what has been done to mess it up.

It's a 1984 Chevy P-30 chassis. You are right, the wiring has been butched to a fare thee well. If I knew a shop who could do a good job I would have the entire chassis re-wired as Chaplain Kent did.

[guy99]

Originally Posted by overlander63

Possible bad ignition switch, or fusible link at the starteer solenoid (lots of fun to check). If your rig has no fuel injection, and no ecm, you can hot wire it so you can get out of there by hooking a wire directly from the battery + to the batt connection on the distributo cap.

I was just under the rig, couldn't access the starter wiring from there. Do you access it from the top?