Check engine light and alarm at startup

[MattyMatt]

Okay, I'm stuck. I've got a 2003 X10 with a predator 310. Upon startup I get a 1 minute alarm and check engine light. Oil pressure, temp and battery are good. I pulled the code 81 which to my understanding could be a lot of things from TPS to fuel pump. I've checked all connection for corrosion around the throttle body and all looked clean. What should I do next? Anyone have a similar issue?

Appreciate any and all help.

Also, before pulling the code o replaced the knock sensor as the old one was looking really rough.

[jpwhit]

DTC 81 is somewhat of a catch all code that directs you to a set of further diagnostics tables in the MEFI diag manuals. I don't know off hand which ECU is on that engine. If it's an MEFI 4 or 5. Just make sure you're using the right manual for your ECU. One of the things covered by DTC 81 is the 5V reference generated by the ECU is out of range. That's often caused by something external to the ECU overloading the 5V reference circuit. But it can also be a problem with the 5V reference generator in the ECU. DTC 81 also includes a bunch of drivers in the ECU for relays and fuel injectors. In any case, you really just have to carefully follow all the steps in the DCT 81 section of the diag manual. Here's the link to the manual for the MEFI 4.

https://www.bakesonline.com/media/re...EFI4manual.pdf

[MattyMatt]

Appreciate the guidance. Half of the stuff in there references a scanner which I don't have. I believe it still gives me a solid path to follow. That said, I want to give some additional info that may que someone looking at this.

The engine is not original. The seller told me the light and alarm has come on ever since the swap. He said a reputable shop did the swap but also told me the boat had been winterized and it had not. I don't see any signs of a cracked block and feel pretty confident the boat runs well but have not tested it under load. Hoping to get it on the lake this weekend or next to check.

What are some simple things I can check?

Is it worth $600 to buy a scanner??

ANY ideas welcome🙏

[curver900]

so the light and alarm go off after a 1 min warm up??? it's not clear

[jpwhit]

Personally, I wouldn't start off by buying a scanner. And if the boat is running well, you can effectively skip a lot of the diagnostics tables to begin with. For example, clearly if the engine is running the fuel pump relay circuit is working. If it's running smoothly, then it's not likely to be an injector driver. The first one I would do is the 5V reference voltage diag table. That's one that could be just out of range and the boat would still run fairly well. See how far you can get w/o a scan tool, and then decide if you want to invest that money or not.

[MattyMatt]

That's great advice, I'll start there. I know just enough to be dangerous, lol. Appreciate the guidance.

[MattyMatt]

so the light and alarm go off after a 1 min warm up??? it's not clear

Sorry missed this question. No, the alarm goes off for 1 minute. It immediately goes off on startup.

Checking ground connections now and trying to figure out how exactly to diagnose this 5v reference others are mentioning. Appreciate any guidance.

[curver900]

." No, the alarm goes off for 1 minute. It immediately goes off on startup."

so when you put the key in and turn it to acc before starting it it beeps for a minute? Then it quits, then when you start it the beep turns off?

I'm trying to understand what the issue is. It would appear that there isn't anything wrong, but i'm not sure i understand what you are saying.. if this is what is going on

1. turn to acc beep stays on for a minute
2. start the motor
3. beep turns off after motor starts

if this is the case check the standing voltage at your batteries with key off, then after starting it check the voltage at the battery again.

Report back what the standing voltage is along with the voltage while the engine is over RPM of 2k

[MattyMatt]

." No, the alarm goes off for 1 minute. It immediately goes off on startup."

so when you put the key in and turn it to acc before starting it it beeps for a minute? Then it quits, then when you start it the beep turns off?

I'm trying to understand what the issue is. It would appear that there isn't anything wrong, but i'm not sure i understand what you are saying.. if this is what is going on

1. turn to acc beep stays on for a minute
2. start the motor
3. beep turns off after motor starts

if this is the case check the standing voltage at your batteries with key off, then after starting it check the voltage at the battery again.

Report back what the standing voltage is along with the voltage while the engine is over RPM of 2k

I'm sorry for the confusion.

Switch on, engine off = constant light on, no beep.
Switch on, engine on = blinking light and alarm on for one full minute. Blinking continues indefinitely.

I've cleared the code several times but it returns very shortly after engine on. I've checked my ground connections everywhere all were clean and tight but I may need to disconnect one by one clean and reattach to be sure. I've checked that 5v is coming from ecm 5v reference. I've checked and cleaned all sensor connections around the TBI. I've replaced the knock sensor. Injectors seem to be operating as they should.

I haven't checked the fuel pump relay per the manual but as jpwhit said, I wouldn't have smooth running if that where the problem. I also haven't fully traced out the 5v reference per the manual as all wires look good and seem to be full seated in each harness. That's said, that's probably what I'll do next.

Also, my perfect pass cable was do for replacemnt as it was bent, frayed etc and was jammed. New cable was delivered yesterday so I'm hoping that replacing that may make a change. My thought being that it could be affecting the tps. I know that's wishful thinking but it needs to be replaced regardless.

Voltage is 12 or greater with switch on/engine off and switch on/engine on.

[curver900]

that helps allot... but before you chase too much more... my free advice would be to put a volt meter on that battery it should be around 13.2v give or take.. not 12 or 12.5 that would be a battery that is not up to the task.

IIRC the light you are experiencing is potentially from low voltage.. batteries are cheap...

[MattyMatt]

that helps allot... but before you chase too much more... my free advice would be to put a volt meter on that battery it should be around 13.2v give or take.. not 12 or 12.5 that would be a battery that is not up to the task.

IIRC the light you are experiencing is potentially from low voltage.. batteries are cheap...

Thanks! I'll check and report back.

[MattyMatt]

Checked batteries and both were 13+ volts. I also found an "extra" wire today that I suspect should go to a one wire sensor. I don't see a sender anywhere near it though. Can someone please tell me what the sender looks like and what it's called? I'm guessing this could be the cause of my CEL. Also, this wire is bundled with the the wires going to the two wire temp sender on the intake manifold.

[curver900]

when you start it up what is the voltage at the battery while running?

IIRC that is not a used connection... i am not close to my boat so i can't say absolutely though. You should be able to search the forum and find the temp sensor with location and wire...