4788 engine start buzzer-gctid404908

[Carlo]

I have a 1998 4788 with 330 Cummins engines. The Port engine pre heat alarm buzzer does not buzz when I first turn the ignition key on. The green indicator light comes on during the pre heat sequence and goes off after about 15 seconds. The Starboard engine buzzer and indicators function correctly. I have studied the engines manuals and wiring diagrams and have been unable to figure out what actually activates the buzzer which I believe is also the low oil alarm. I was told that the sensor beside the oil pressure sensor was a low oil sensor, but after looking it up and speaking to our Cummins Dealer it appears that this is a temperature sensor. Has any one ran into this or can point me in the right direction to solve my problem?

Thanks

Carlo

[ksanders]

Does the one on the flybridge work?

That might help isolate it to a buzzer or a sender issue.

[cosmo777]

Switch the port buzzer and starboard buzzer.

See if it follows the buzzer or stays with the engine.

[higgins_jr]

Carlo, I had the same issue with mine. It turned out to be a faulty oil pressure switch (vs sender). The switch looks like a "sparkplug" next to the sender. My auto electrician grounded the circuit and the buzzer in the pilothouse worked. (I had already bought and changed a new buzzer thinking that was the problem.) The part is available from Cummins but the connector may be a tad different - an minor "adaptation" of the loom connector end with a box cutter will make it fit snugly into the switch end. I remember the local Cummins shop here didn't have a clue about the part or part number. I believe the number is in the manual somewhere. From recollection, there are several switches in the alarm circuit that can trigger the buzzer - coolant temp, oil pressure, water in fuel, alternator. There may be others, but try the oil pressure switch first.

Cheers John H

[higgins_jr]

Carlo, if your problem is the oil pressure switch, the part number is 3408608. Your local diesel or Cummins parts shop should be able to get it for you.

Cheers

[Guest]

check the connection first. I had a similar issue and tightening the wire on the sending unit fixed it with about 15 seconds of effort. A big win with my skillset.

[Carlo]

Thank you for your suggestions. I have found that there is +12 volts on one side of the buzzer when I turn on the key but no ground from the the oil level sensor switch on the other side of the buzzer. The starboard engine buzzer works fine. As part of my diagnosis, I disconnected one wire on the oil level switch on the starboard engine and the buzzer does not go on when the key is turned on. I hurt my back a bit ago so crawling in and out of the engine room is painful and a challenge. Being 6'2'' and 270 pounds doesn't help either. To continue the trouble shooting, I meditated for 10 minutes to get my body flexible enough to crawl around the front of the port engine to check the oli level switch connection on the back side. The physical switch is totally different between the port and starboard engine. The port engine has a hex shaped switch with a two wire slip on connector which I slip off and on several times to clean the contacts. It looks like a factory original. This didn't solve the problem and unfortunately I didn't have a jumper wire with me to bridge the terminals in the connector to simulate the switch. The switch on the starboard engine obviously has been changed. It looks like a spark plug (as one of you mentioned) and has two wire terminals for a crimp on fork wire connector. As I still had to pull the alternator on the starboard engine due to low voltage I decided not to crawl back in the backside of the port engine today. Tomorrow, after limbering exercises, I will go back in and bridge the connector wires. I fully suspect that the switch is the problem. If it is, as also mentioned by one of you, the dealer had no info in his manual to show this switch. so getting a new one may be a challenge. It is definitely not the oil pressure sensor.

[higgins_jr]

Carlo, I think you are on the right track. Bridge the harness connector and see if the buzzer goes off. If it does, then I think it's the switch that is the issue. I changed the port sender and switch reaching down from the top (with a mirror at 45deg resting in the bilge (and light). You should be able to get the harness connector off the switch reaching from the top as well, lifting the little lug that holds it in place and you can bridge it that way before unscrewing the switch. If you need to remove the switch, you don't loose much oil dribbling out, but a cap to screw finger tight back in helps. A long socket and ratchet from the top worked fine for me.

The low oil pressure switch (vs oil level) body that I removed was slightly smaller (if I remember correctly) than the replacement (1" vs 1-1/8" socket), but the replacement was 1/8"NPT so it went in easy. I did the harness lug mods (shaving a sliver of plastic from each side to fit into the switch connector) from the top before I screwed it in. The tad of slack in the wiring harness helped.

I too had a devil of a time getting the local Cummins shop to confirm the part number. I searched the internet and finally found a Cummins Quickserve Online Parts page with the detail. In their Electronic Parts Catalogue - Option detail - EC8281-01, Group 15.05, Graphic ec404gb, Film card K date 05-JUL-04. I can scan/fax if you want. Send me a private email with your details. Try EC8281-01 Low Oil Pressure Switch (Replaces EC8017) (Remarks: Switch operates on decreasing pressure at 18+or - 2PSI.) It says cannot be used with Cummins supplied engine wiring harness, but I believe that's more about a slight change of harness connector which I adapted to fit.

I ordered it from Rincon in San Clemente CA with the part #3408608 about a year back ($75). They found it with that part number and it took a couple of weeks to source and deliver. There weren't many around.

Have fun. Cheers

[Carlo]

Higgins

Thanks for your info. I did confirm today that it is the sender or transducer. I bridged the two wires connected to the sender and the buzzer rang. So now that we have established the problem, the next problem is sourcing a new one which you seem to have the answer too. I would certainly appreciate your info. If you could send it to me at [email protected] I would be truly greatfull. I got the new alternator installed today and it works great.

Carlo

[Guest]

Because you're going to need somebody with smaller physical attributes to work one the outside of your engines. And sooner or later you will have to. so hopefully your daughter can capture some young flexible man who would be looking to remain in your good graces and willing to submit to the torture required to get to the outside of those engines and actually do anything.

[Guest]

Because you're going to need somebody with smaller physical attributes to work one the outside of your engines. And sooner or later you will have to. so hopefully your daughter can capture some young flexible man who would be looking to remain in your good graces and willing to submit to the torture required to get to the outside of those engines and actually do anything. That's what I had to do.

[ksanders]

Scary wrote:
Because you're going to need somebody with smaller physical attributes to work one the outside of your engines. And sooner or later you will have to. so hopefully your daughter can capture some young flexible man who would be looking to remain in your good graces and willing to submit to the torture required to get to the outside of those engines and actually do anything. That's what I had to do.

Thats too funny!!!

But in all seriousness I am able to get around things and get to the outside of my engines, and I'm no horse jockey myself.

Then again, when they had them out I removed that gigantic waste tank. Sorta makes things easier.