Bad Starter relay?

[Johnscsx]

This morning my 2007 Lucerne CXS would not start. Turn the key, dash lights come on, but no crank whatsoever. I have had this problem twice before in the last year, but it was intermittent, and I never got to the root of the problem. This morning it was a little easier to troubleshoot though, as the silly car would not crank at all. And this was after having just started it successfully an hour earlier. No reason to believe there is a battery problem, the battery is only a year old and sits comfortably under the back seat. Headlights nice as strong, just won't crank.

I replaced the starter about a year ago, but because it's under the intake manifold, you can't easily check the electrical connections.

I opened up the fuse box in the front of the engine compartment, on the passenger side. There are 11 little relay boxes in there, of four different types. One of them, in location R6 is marked "RUN/CRNK". I pulled it out, but it's all plastic encased, so you can't see inside without prying the lid off. So, I swapped it with the R1 relay, marked "COOL/FAN 1", which is marked with the same part number. And guess what? She started right up. So until I can get a new relay, I probably don't have use of one of the front radiator cooling fans? If that's what "COOL/FAN 1" means

I'm starting to wonder if these relays are reaching the end of their useful life. (Car has 97K miles, and is 10 years old) I just ordered a bunch of these things, and plan to replace them all. They had a special deal on ebay, 10 for $26. Part is marked 12193614, with the last four digits in bright white.) I think RockAuto.com was selling them for just over $5.

I will also replace the micro relays and other two types of relays, but I'm still tracking down part numbers.

Another possibility that the relays themselves are fine, and it may just be loose/corroded sockets? I should probably spray some contact cleaner down there when I replace them.

So now my question to you other Lucerne owners out there - have you ever had one of these 12193614 relays go bad? They are marked on the fuse box as follows:

R1 COOL/FAN 1
R3 CRNK
R4 PWR/TRAIN
R7 COOL/FAN 2

I think that R4 powertrain relay powers the Powertrain Control Module. I doubt if the car would run without it, so maybe replacing these relays before they go bad would be good preventative maintenance. If your car doesn't start, and you have to get a tow to a garage that could be very expensive for a relay that costs less than $5.

One of those micro relays, in position R6, is marked "RUN/CRNK". I wonder how that relays differs from the larger relay marked "CRNK" ? It's rated at 15 Amps, and here is the data sheet for it:

http://www.farnell.com/datasheets/1...4.1542597514.1494627264-1520163381.1494627264

It says the relay has an electrical indurance of 100,000 times. So, you supposedly would have to start your car more than 27 times a day over a period of 10 years for this thing to wear out. Obviously I didn't get nearly that much life out of my own starter relay. Maybe some moisture got in there? Or the extreme heat under the hood contributed to premature failure. Too much engine vibration? Manufacturing defect? Loose or corroded connection in the fusebox? An electrical surge greater than the device can handle? I can only guess.

I'm not sure of the difference between the function of the smaller starter relay, and the larger one. Anyone know? I do know that this car has an automatic start feature. When you turn the key you're really just telling the computer to start the car for you. It doesn't matter how long you fully turn the key, because when the engine starts the computer will direct the starter to disengage the solenoid. I think that is part of the necessary electrical infrastructure for the remote key start option, and also ensures the driver can't grind the starter by trying to engage it while the engine is running.

And, FYI, here is the car owner's manual, which also contains fuse box info:

https://my.gm.com/content/dam/gmown...7/buick/lucerne/2007_buick_lucerne_owners.pdf

I've heard a lot of reports from other owners on this forum about the car just quitting for no reason at all. Something like that could be caused by a bad relay. Hit a hard bump with a critical relay that has marginal contacts, like your ignition or fuel pump relay, and that could cause some intermittent problems that would be very hard to diagnose. Maybe it makes sense to replace all of the relays on this car after it passes a certain mileage, say 75K. It's a lot of work to track down the new part numbers, but these things don't cost much, and if they can prevent an inconvenient failure, it may be worth the money if you can do it by yourself and shop around for the best prices before a failure occurs.

 

[Johnscsx]

I just went through the fuse boxes under the hood of my 2007 Lucerne CXS (your fuse box may vary, depending on the model and year), and under the back seat. Here is a list of the relays:

Relay type 12193614. Under the hood, in the R1 (Cool/fan 1) , R3 (CRNK), and R4 (PWR/TRAIN), and R7 (Cool/fan 2) positions. The same relay can be found under the back seat in the R14 (Rear Defogger), and R15 (Electronic Leveling Control Compressor). So, you would need a total of 6 of these. $5.30 @ Rockauto.com = $31.80

Relay type 12193612. Under the hood in the R2 (Cool/Fan), R8 (wiper), and r10 (wiper hi) positions. So, you need a total of 3 of these. $7.42 each at Rockauto.com = $22.26

Relay type G8VA-1A4T-R-GM. Under the hood in the R6 (Run/CRNK), R11 (AC). and R12 (AIR/SOL) positions. 3 @$4.43 mouser.com = $13.29

Relay type G8JR-1A7T-R-GM1. Under the hood, position R9 (air pump) only one of these in the whole car. Rockauto.com = $5.12

Relay type G8V-1A7T-R-GM under the back seat in positions R1 (Retained accessory power), R2 (Park Lamps), R3 (Run option), R4 (Daytime running lamps) and R6 (Trunk release). 5 @ $3.62 at Mouser.com = $18.11

Relay type G8V-1C7T-R-GM Under the back set in position R7 (fuel pump), R9 (Door Lock), R10 (door unlock). 3 @ $3.62 at Mouser.com = $10.86

Add it all up, and without shipping you're looking at about $101. That's probably less than the cost of a short distance tow, much less the price to diagnose & repair the problem, and you could probably replace all the relays in about an hour. If you really shopped hard, you could probably get better prices too. For example, I got a deal on ten of the 12193614 on ebay for just $27, as I have another car that uses the same relay.

I'm constantly hunting for practical ways to increase the reliability of my old cars, but it's sometimes hard to predict what will go wrong next. You don't want to replace parts that are working OK, but you also don't want to ignore parts that may be near the end of their useful life. One trick I've learned is to take my car to Firestone and pay them $10 for a thorough "pre-vacation trip" inspection. When they're done they ALWAYS find something wrong that I overlooked, and there is even a list of the OEM replacement part numbers on the quote. Of course they offer this service for so little money because a lot of customers will get the repair work done there. But, me, being a poor man, I'll take their list of proposed repairs, purchase the parts on the internet for half of what they are quoted for, and do the work myself with the help of some youtube videos. This usually involves buying a new tool or two, but tools are usually also useful in the future.

Now here is an idea for all of you entrepreneurs out there. If you had a website that could figure out all the relays in a specific car, using the VIN, and then ship them all to you, that would be worth a lot to somebody with an old car that wants an easy and cheap way to increase the reliability. (You buy the relays in bulk from the manufactures for $2 or $3 each, then sell all 21 of them for $4 each. That would be a profit of at least $20 on an order like this, and you would be saving customers a great deal of time hunting down part numbers and the best priced vendors) You could even take the business idea one step further, and offer a full set of emergency replacement fuses for a specific vehicle, for somebody to keep in the glovebox in case of an emergency. (The spare fuses they offer in the fuse boxes are only a small subset of all the fuses that keep the car running.)