Grid heater relay source

[dpuckett]

I have been searching here and elsewhere for 30minutes, and have had no luck, so I'm going to just ask. I saw a few years ago, some commpany had relays identical to our grid heater relays for real cheap, I'm thinking <$20 apiece. My truck and Mom's both need a relay, and I found I didnt bookmark the page, so I'm totally lost. Does anyone remember or know where I may look?

Thanks,
Daniel

[PToombs]

Positive I saw it on TDR. Maybe here too.

[Ace]

I remember seeing that too. It's some online electrical supply house you can get them from, but I forget where...

[dpuckett]

Philip gave me a part number on Cummins Forum- 120-913. On to find them for sale.

DP

[Richie O]

Why do you need a special relay? Won't any solenoid rated for the amps work? Like a cheap ford starter solenoid.
Another question, why do we have 2? Are they activated by the same source or do they have seperate parameters to come on?

[Ace]

If it's not completely toasted sometimes they can be refurbished by taking them apart and cleaning them.

[Mark Nixon]

Richie, there's 2 solenoids because the heater actually has 2 heat strips in the "grid" heating element.
Both of those black wires are POSTIVE, the grounds are internal once the grid heater is bolted in place on the intake.

On 2nd gens, the solenoids themselves are interchangable, but not the mount.

Dan, I have a good 1stgen 1 or 2 around.

Mark.

[Richie O]

Richie, there's 2 solenoids because the heater actually has 2 heat strips in the "grid" heating element.
Both of those black wires are POSTIVE, the grounds are internal once the grid heater is bolted in place on the intake.

I knew that. I was just wondering if they came on at different conditions. The actuator wires are seperate. I thought maybe 2 came on during start up then maybe 1 would cycle after its running, something like that.

[Philip]

On engine start both grids kick in. After the PCM sees the RPM signal it only uses one grid at a time. It just cycles between them.

[Richie O]

On engine start both grids kick in. After the PCM sees the RPM signal it only uses one grid at a time. It just cycles between them.

Thats what I was after.

[Mark Nixon]

ER, what about the non-intercooled trucks?
They are "blind" to rpms.

Mark.

[Philip]

NonIC trucks has a stand alone controller. I am not sure on how it operates.

[dpuckett]

I think the nonIC trucks use the intake temp sensor to regulate the post heat. I'd have to dig out my FSM and double check.

I gave the part number to my local start/alt rebuild guy, and he came up with a picture of a single little post (case grounded) contactor. He made a phone call, did some more digging, and found one that was like the OEM (120-903, I think- box is in the truck). They ran $25 each, and I replaced both of them. I found some online for $15-18ea, but this guy has treated us VERY well in the past (rebuilt a 1stGen alternator for Christina and me for no charge), so I figured I'm still ahead overall.

I installed them, made 2 line hauls to StLouis, and it fired right up at 1:30am, had the post heat, and everything.

DP

[BobS]

Try: http://www.mouser.com/search/ProductDet ... 02-120-901


Mouser Part #: 802-120-901
Manufacturer Part #: 120-901
Manufacturer: Stancor
Description: General Purpose / Industrial Relays SPNO 12VDC
Price (USD) $16.64
Silverlight Page 1,967, Mouser Enhanced Catalog

Data sheet at: http://www.stancor.com/wrdstc/pdfs/Cata ... 052_53.pdf