Collateral Damage – Starter Relay RunAway

[ActionStarCBRxx]

I posted earlier (http://www.steelsoldiers.com/cucv/32411-cucv-m1008-runaway-starter-2.html) about my runaway start issue. As you all suggested... it was the starter relay. I replaced that and it appears to address the issue. My problem now is in assessing collateral damage.

Before I replaced the relay, I replaced the starter switch, hooked up the battery and the starter started running again. Within 30 seconds, I started seeing smoke by a block (Engine Wiring Harness Block) that is mounted right next to the master cylinder/power booster. It looks like half the glow plugs go to the top terminal and the other half goes to the bottom terminal. There are also two orange wires that come off the bottom.

With the batteries plugged in/hooked up I put a volt meter on the top post of the block and it reads 24 volts. When I tested the bottom post of the block it did not read or show any voltage.

My question now is... Is this normal or should both posts read 24 volts? What are the next steps if this is blown/busted?

Thanks again for your help!

Kelly

See Attached Picture of Block

 

[Crash_AF]

That is the glow plug relay, it should show 24V on the top post and nothing on the bottom as you describe when they are not engaged. To test the relay, ground the blue wire and the relay should click and you should get 24V on the other post. That 24V should quickly decrease to about 14 or so volts if all of your glow plugs are functioning properly. If not, it will go down to a higher number, how high depending on how many glow plugs are burned out.

If the glow plugs are split between the two posts, it is hooked up INCORRECTLY and the plugs connected to the constant 24V are smoked. Hopefully they didn't swell from having 24V to them constantly, but that's unlikely. Both sets of glow plugs and a small orange wire should be connected to the bottom post in your pic.

If I'm looking at your picture correctly, there is a jumper between the two posts on the relay, that is incorrect as well. (Hard to tell though since the white wire with the yellow ring terminals extend off the top of the pic.) The two Orange wires should be one set of 4 glow plugs and there should be another one just like it for the other set. There should only be the one red wire from the resistor block mounted to the firewall to the top post and the two sets of large orange wires and one small wire on the bottom post.

Later,
Joe

 

[Michael]

That is a picture of some messed up wiring. You need to look at appendix F in the -20 TM and read on the list for a while. Also looks like the original glow plug relay that should be replace even if it does still work.

What it should look like:


http://1plant4u.smugmug.com/gallery/2338485_vNWfN#122363277_22JU8

 

[m38inmaine]

Also, that is the old plastic style glow plug relay, I would replace it asap, they were prone to sticking as well. FLMV.net has NOS original replacements.

 

[Crash_AF]

Ok, I retract a little bit of my last post... the only thing that is NOT correct on that GPR is whatever the white wires with the yellow terminals are.

Where do those go? They are not part of the original wiring.

Later,
Joe

 

[ActionStarCBRxx]

Just a quick note of thanks for all your help. I sincerely appreciate it!

I am looking at the diagram for the glow plugs and what I have does seem a little messed up.

One thing I did not mention about my truck (M100 is that the glow plugs are actuated by a push button. The original relay/switch under the dash for the glow plugs has been disabled. (I bought it that way so dont give me any slack!)

I think my next step is to walk through the voltages off all eight glow plugs and see what the voltage reads...

I started the truck last night, and it started really quick (quicker than before the runaway starter issue) but the weather was warm in the 70's/80's. Regardless I dont feel comfortable driving it until I get this resolved/confirmed.

Again thanks for all the help!

PS Whats wrong with buying a glow plug relay to replace mine from a regular auto store? Are the ones from the MIL sites better? (just asking... not sure what needs to be replacement OEM and what can be picked up at the local auto store)

 

[Michael]

The only way that I can see what you have in your picture working is if the two pairs of white wires with the yellow terminals go to a switch and you do not actually use your relay.

Nothing wrong with using a parts store relay. Actually, there is not much wrong with the setup you have, just a lot of current going through those wires. There may not be any overload protection either so if you short one of the wires it could start a fire. I would inspect where the wires go through the firewall.

 

[Crash_AF]

I agree with Michael... it looks like you have a switch bypassing the entire relay, that's not good. What you need to do to keep it manual is eliminate the white wires entirely and run a wire from the post with the blue wire to a momentary switch, and from the switch to ground.

Later,
Joe