Glow plug relay questions

[AJMBLAZER]

I was just reading our new FAQ (thanks mods ) and saw the gp relay mentioned.
http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=21464

Sure enough, mine looks like the second from the bottom. Probably ought to replace it.

Crash_AF mentions the two possible replacement relays, the ST85 and the ECHGPR110. The ECHGPR110 is nearly $30 more than the ST85 so I was wondering if it offered any advantages to warrant the higher price?
Are either of them superior?
Either a direct bolt in replacement?

Would either of these be a problem if I eventually converted the truck to 12v start?

 

[Crash_AF]

Supposedly the Powerstroke relay (GPR-110) is the last relay you will ever buy... or so I've heard from several 6.2 owners.

They are both civvie applications, so they are designed to work with 12V systems, so I would anticipate no issues with a 12V start system conversion.

Later,
Joe

 

[AJMBLAZER]

Okay, so worth the $30 extra then. Check.

Electrical stuff confuses me easily so forgive me if my questions are obvious. This relay is after the 24 to 12 volt reduction, correct?

 

[Crash_AF]

Actually the CUCV glow plug system doesn't receive 24V if it is working properly so it will work pre or post conversion.

From what I understand, the Powerstroke GPR has heavier contacts and is rated for a longer 'on' cycle than the GM equivalent... this equates to a longer time before the contacts take enough arc damage to cause intermittent operation.

Later,
Joe

 

[AJMBLAZER]

Okay. I barely have my head around the basics of diesel operation and the 24 volt system just mystifies me so far.

Thanks!

 

[ida34]

Just a note. You will measure 24 volts at the input of the relay until the glow plugs cause a current draw. The load will then show 12 volts or so but the load of the multimeter is not enough to drop the 24 volts down to 12 volts. This is why things burn out quick when one glow plug goes. When I glow plug burns out the current draw is lower and that causes the voltage to go up coming out of the big resister. To do the its job right the resister needs to see a load from all 8 glow plugs. When one burns out the voltage goes up to the other ones. This burns more out and so on until they are all burned out. I had a connector come off one glow plug. Before I knew there was a problem I had three plugs burned out. It may take a while for the second plug to burn out but the rest burn out much quicker. The point is, you will see 24 volts at the relay if you just probe but when the glow plugs are on the input to the relay should be around 12 volts.

 

[Michael]

I went back and edited my post today. I used a 109 relay that looks just like the 110 but is half the price. I didn't see any specs so it probably has smaller contacts inside.

The 109 and 110 relays will bolt up with the same holes as the original relay. They don't come with nuts on the posts and they aren't the same size as the original so you will need to get some while you are at the store.

 

[AJMBLAZER]

So what is the difference between the 109 and the 110 then?

 

[Michael]

Found this on the web. I personally haven't had any trouble with my 109. Surely they don't charge that much more to rotate the base 90 degrees.

And I can tell you this from my own experience, GPR109 is not really the same thing as a GPR110. It looks the same, same bolts, same molding on the plastic, but not the same. Here's my story.

We went to NAPA and had the guy bring out both a GPR109 and a GPR110. They look identical from the outside except that mounting bracket is 90 degrees counter clockwise. I even had him look up the parts specs and they even pull the same electric specs. So I bought the GPR109 and we took it back to change out the relay. We got the relay on the posts but had a bit of trouble getting the wires to stretch that extra inch and a half or so to get it on the rotated posts. Well, we got it on and started to put the bolts on and **SNAP**...yep...the pressure from the stretched wire pulled the bolt right out of the plastic housing on the relay. It peeled like an old potato. Boyfriend threw a wrench across the yard. Dangit. Well we spent the next hour trying to get that GPR109 off, as the thing was such a cheap piece of crap, one of the bolts stripped quickly and with only using end wrenches. After getting the nut off the stripped bolt..the story continues...

And so back we went to NAPA, to get a GPR110. After comparing the GPR109 and GPR110 and taking apart the broken 109 and my old original OEM relay, here's what we found:
The original relay (and the GPR110) are much heavier and made out of much thicker plastic than the 109. Also after taking the two apart, we noticed that the original relay had insulation on the copper wires and heavier wiring on the inside, which the 109 did not.

Buyers beware. As the GPR109 LOOKS the same as the GPR110, from an electrical standpoint I don't believe they are. I was surprised at how quickly that GPR109 just snapped into pieces, just from the pressure those large terminal wires were putting on the bolts from being stretched.

As they might function, I will be a bit curious to see what these GPR109's do in any given amount of time, as it was obvious to me they are not very well constructed.

Hey all
Well, I'm a hard sell, so I contacted Napa and the manufacture Echlin who makes Napa's GPR. According to them the relays are the same on the inside. Only the mounting situation is different. This is a copy of email I sent to them and there reply:

Web Site Refer : Napa
Message : Hi there Trying to find out the difference between a GPR 109, GPR 110 and a GPR 111. I have a 1999 F-250 Ford diesel and it calls for a GPR 110 glow plug relay. But I have heard of people using the GPR 109 in the same truck because of the cost savings. They are saying the only difference is the mounting bolts and that the internal parts are identical. Can you verify this please. Thanks so much, Randy Lemieux

There reply:

Dear Customer, Yes this is true.

 

[AJMBLAZER]

Hmmm, did you have any install difficulties with yours?

 

[JohnFire]

ok kinda on the same subject kinda not. I have the 110 for mine, and have held off installing it since it came with no wiring instructions. Most relays I have ever put in always had a basic schematic on or with them. would I be correct in thinking the main power input is on the ignition side of this relay or shouldn't it matter. Also this question is to help me understand how they are activated for this application and might help with Swede's starting problems. When I test the wires for the relay. The one that is listed for ground, I believe it is the blue one off the top of my head(please correct if I am wrong) is getting 0Volts when ignition is off. 1.5V with the ignition one and the glow plugs cycling, and 12V when they are done. The pink which is listed as ignition(again please correct and I will edit this) 0 Volts when off, 12V when cycling and 12V when they are done. When done I mean the truck is running cause they completed their cycling. I get 12V on the output side of the relay when they are cycling and 0 V when they are done. Which is how it should be as far as I know. Now my truck is working fine, and I converted to 12V last year. Swede hs been having problems. He gets 12 on both connections all time, and a if the truck is running he is getting 24V comming off the resistor block, and still comming through the relay. Then it starts to smell like something is burning. My guess is glow controller. But if anybody can pipe in including Swede to make sure I am saying this correct. I would love to know what should be what here and how the 110 should also be wired. Cause mine is stock relay, and his came with the 110 style. Plainly looking at the 110 you can tell it is a much better relay than GM put in these things.

 

[Michael]

I didn't have any trouble installing the 109. My last quotes came from a powerstroke forum. CUCVs have enough slack in the wire to put about anything you want in there. The ST85 is also a starter relay and it looks like what the military used, so it might actually be the best choice.

As far as how the relay works, it is triggered by completing the ground. You should see 12v at the PNK/BLK wire whenever the ignition is on. You would also pick up 12v at the LT BLU wire after the controller card has cycled off since you are just at the other side of the electromagnetic coil. You could measure resistance to ground and it should be infinity after the card has cycled off. The controller card completes the ground through the LT BLU wire. You can also jump this wire to ground to manually trigger the relay.

The RED wire from the resistor should read 24v with no load with a digital volt meter. If you have good glow plugs the voltage will drop to about 12v when the relay is activated and you should see 12v at the ORN wire. If you have temperature compensating plug like AC60G the voltage will change as they heat up. I think it will increase but have never observed this. I don't think it matters much which wire goes where since a relay is just a switch activated with a electromagnetic coil. You can also jump this connection with a heavy gage wire in an emergency to start the truck. You can get some impressive sparking since there is a lot of current flowing if you have good plugs.

 

[CCATLETT1984]

the light blue wire is the switched ground.

 

[Michael]

Sorry about that. I corrected my post above.

 

[AJMBLAZER]

Okay, so since the ST85 and the GP109 are so much cheaper I'm likely going to go with one of them.

I'm sort of undecided...any real advantage to either?

 

[AJMBLAZER]

Does anyone know the vehicle applications for the ST85 and GP109's? Thinking that NAPA CDR valve isn't going to work so I might just order everything from Rock Auto.

 

[AJMBLAZER]

So I checked with NAPA and they list the ST85 as a Dodge starter relay used on a variety of vehicles from the Caravan to the diesel trucks.

The GPR109 is listed as a Ford diesel glowplug relay used 83-91. Here's what rock island shows as a:
"1989 FORD F-250 PICKUP SUPER CAB 7.3L 445cid V8 DIESEL MFI (M) : Ignition : Diesel Glow Plug Controller"
http://info.rockauto.com/Airtex/1S5421.jpg
Anyone else think that looks like the right part?

 

[Michael]

Looks the same to me. Did you find the dealer here that is selling NOS relays?

 

[AJMBLAZER]

no...?

 

[AJMBLAZER]

Well, I bought the 109. Do the leads go to a specific post or does it not matter?