In case anybody in the future needs Digikeys part number it's 255-1240-ND. I bought 4 of them years ago and it wasn't my problem. They are Panasonic relays rated at 15 amps.

 

That part number is just the Digi-Key in-house part number (or item number) for the manufacturer's (Panasonic) part number, which is JSM1-12V-5. Thanks though.

 

dammit i just joined this club

hope i can find some stock somewhere

 

I don't think there will be a permanent shortage necessarily. Check back with Mouser Electronics or Digi-Key from time-to-time. They are the two 800 lb gorillas of the electronic supply companies out there these days and as far as I can tell have them on back-order. You may want to check with some of the other smaller, independent, supply companies too.

Personally I wish I could find a relay that had even higher contact ratings like 20A for example. DC current (the arcing) can be brutal on relay contacts, especially with inductive loads like a door solenoid and a 20 amp version would last longer I'm sure due to it's higher contact rating.

Oh well, it is what it is.

 

Today I decided to see who, if anybody, makes a higher rated contact than the 15A rated OEM relays that would be suitable. I was even willing to explore the possibility of finding a 20A (or more) relay that was sealed and mount it/them "off board" and outside the black enclosure if need be, and run some separate small wires over to the circuit board. Not quite as elegant as a pcb mounted relay, but definitely a viable option in order to get a much higher rating on the contacts, which as we have all seen, is what is suffering under the relentless arcing each time the door locks are activated. I think getting some really beefy contacts will solve the problem for good.

After much looking at data sheets, etc, I came across:

NEC (brand) part # EQ1-31000S. The contacts are rated at 30A at 16VDC, compared to only 15A on the factory OEM relays. The coil current draw is a bit higher at 1000mW (vs the Panasonic's 640 mW) but I think this would most likely not be a problem either and well within the design-range of the door switch contacts on the car door.

I checked out the physical packaging (L, W, and H), and the pin layout and they are, in my mind, so close as to warrant a further look-see. It is a sealed, SPDT, Form C relay, and the pin arrangement is identical to the Panasonic JSM1-12V-5 relay.

Mouser is almost out of them (only 9,433 on hand ) so I think I'll order a couple to check them out. They're for cheap at $1.68 each. These are current production, so I think a good many other suppliers will carry them as well, especially since NEC is a well-regarded Japanese electronics company and makes a wide variety of other products.

Just wanted to share this with everyone who likes to save a buck and doesn't mind doing a little desoldering and resoldering every once in awhile. If these pan out, they may solve the problem permanently instead of just replacing the relays with another identical piece, only to have them eventually fail too.

 

Lonestar, I will definately be interested in a more permanent solution. I'm not gifted in the desoldering arts and would like to fix these relays for good. Keep us posted after you try these new ones.....

 

PM sent

 

OK, if my math is correct, these relays are drawing 56% more power from the Integrated Circuits on the door control module. Most devices can handle plus or minus 10% but this is way over that so beware, you may burn out the IC that drives the relays. The door switch is just an input to the IC, but it is the IC that drives the relay. I suggest you stick to the 20 amp relays or the stock 15 amp relays to avoid over loading the IC and end up replacing the whole door control module.

 

Yikes, I didn't look at the circuit to see if the door switch directly closed the circuit to the relay coil or not. Didn't realize it was IC driven. Glad you mentioned that.

Went back and double checked and guess what? Mouser's online data summary is wrong.
Mouser publishes data "summaries", or abstracts, for a great many of it's products in their catalog and online (where I have been looking) and they list the coil power consumption as 1000mW, but when I looked at the actual pdf data sheet published by NEC, it shows 640mW. Strangely, Mouser's actual catalog listing is correct.

Just to verify, I went to another electronics suppliers webpage and checked there too. Sure enough, the NEC data sheet they show is the same (640mW). Just to cross-check even further, I verified that the NEC coil resistance is the same 225 ohms as the OEM Panasonic 15A relay, so that proves that the coil power has to be the same, given the same voltage. That is unless DC circuit Ohm's Law has changed since last I looked.

Anyway, thanks for mentioning that.

Btw, while I was checking again, I came across a Panasonic relay that is designed to be a smaller version of the JSM that we have in our door modules. It is the "JJM" series (also a 640 mW coil) and occupies a little less real estate but coincidentally, is available in a higher contact rating of 20A (the JSM series maxes out at 15A) Apparently the NEC's EQ series is designed to compete with Panasonic's JJM series and be smaller but yet offer 30A max.

So, it seems there are two good alternatives here:

Panasonic JJM1-12V (smaller package and identical pin-out) @ 20A

or

NEC EQ1-31000S (smaller package and identical pin-out) @ 30A.

Guess which one I'm inclined to use?

 

You are correct, as long as the coil resistance is the same as the other relay, then the coil current draw is going to be the same. One more thing, the pin spacing does not allow much room to fudge with. Hopefully they will fit if the feed through holes are large enough on the circuit board. Thanks for the research.

 

Yup, the pin pattern is the same as the OEMs. Already verified that.

Not sure when Panasonic and NEC introduced these slightly smaller series relays, but it's possible that it was after '97 which was when the first C5s started rolling out. Usually the parts suppliers have to get testing/approval from GM well before production begins and that's why (possibly) the earlier (JSM) versions were used and this board was designed in '96. Bad part is (in retrospect), the JSMs only have 15A as the highest choice available. Cost is always an engineer's worst enemy too.

 

My passenger door doesn't un-lock either by using the fob or door switch. I replaced the middle relay and am still having the same problem. I purchased the relay from Newark and it took two weeks for delivery from the UK. I'm now considering replacing the actuator but at this point GM can troubleshoot it for $100 and eliminate all the guesswork and wasted time and money. (???)

 

There are two relays you have to replace on each board....

 

No kidding. Which other relay? The post I read said the bottom one is lock and the middle one is unlock. I don't know what the other two are.

 

I had to replace the lock & unlock on both boards. Also, I lubed the mechanism including the area where the rods rub on the guides.....

 

Swap the driver's door control module with the passenger side and see if the problem travels to the other door. That will help you determine if the problem is in the module or actuator. If the module is the problem, I have a spare module I could sell you. Drop me a PM if your interested.

 

I'm probably wrong but, if I remember right, the two boards are different. I think maybe the driver's side board has different connections? The driver's side board probably controls more functions or something....

Hopefully I'm wrong....

 

I think you're right about the R/H and L/H boards being different. I think the LDCM board has additional functions like window control for both doors and I think the outside mirror control circuitry is in there too. As far as I know though, the door lock relays are the same on both sides.

 

Trust me, they are the same. I have swapped them, I have told countless others to swap them and it does work. Pop open the black box and look at the card and you will see they are identical.

 

Interesting then, that there are two different GM part numbers for the right/left DCMs:

'97-'99 LDCM 9352881
'97-'99 RDCM 9352891

'00-'04 LDCM 9389689 (Superseded by 10342159?)
'00-'04 RDCM 10435192 (Superseded by 10342160?)

Perhaps the door lock/unlock/window functions are the same and that explains why a RDCM will "work" in a LDCM position say, for example to test a door actuator or window motor, but there are obviously differences or there wouldn't be two different part numbers and prices.

Although it's possible, or even likely, that there have been GM part number supercessions to these, the fact remains that there are different numbers for right vs left.