View Full Version : 2005 Gauges not working flashing ECU

08-21-2013, 08:29 PM
I have a 2005 prostar 205 v and the gauges are not working. They try wiggle when I first turn the key on but that is it. The digital display on gauges is working and is flashing ECU.
Here is where I am at with my trouble shooting so far:

Have used the boat about a dozen times with gauges not working and boat runs great, but I want to fix this annoying problem.
Have fully charged batteries (boat dual battery set up) and clean connections. Have checked voltage under dash it does match voltage reading at battery. Have check ground block and even temporary tied it in to both bat. neg post (did not help).

Took it by dealer and they checked MMDC, ECU (with code computer), some new gauges, fuses, and the relays. With two service techs and myself trouble shooting we could not find the problem. Only the digital readout works giving lake and water temps and the infamous "ECU". I have checked, checked, checked and rechecked the voltage difference at the ground block and the problem does not appear to be there unless one of the ground wires has a short in it.

Also, I checked voltage at back of one of the gauges and it is getting power Ė6.5v from the MMDC.
That is what I have. I have unplugged them all gauges and even tried a new gauge from local MC dealer. Also, found out the 4 wires on my boat are as follows:
orange: 6.5v power from mmdc
yellow: CAN_MMDC --- this wire is digital feed
Back: Ground ___ All my gauges appear to have good ground
Blue: power for lights

From CAN MMCD OUT Harness (what Mastercraft calls the harness, not MMDC) I have 12v at pin E (from battery) and 12 volt at pin F when ignition is on. Problem does not appear to be here.
Also checked the ground at pin D and it has a good ground. I plugged the out harness back in and checked voltage at gauges. I checked ground first and it was good. I also tied a wire back to the ground block to ensure a good ground. I checked the oil pressure gauge since it was on the end and the easiest one to get to. I had 6.5 volts (gauge power to it from pin B) at the gauge, but the control wire seems to be the problem. I am not sure what the voltage should be here.

Also, I traced the two CAN (digital wires the provide all the interments with info) on the MMCD-IN Harness to the ECU. My problem does not appear to be a bad between the MMDC and ECU.

I am scratching my head on what to do next. I will post some pictures that might help other out.

Please give all suggestions. I am planning to take boat back to dealer in few weeks if I can figure it out, but donít want to throw give up yet.

08-21-2013, 10:10 PM
Wow, sounds like you've tired a lot so my suggestion may be a longshot. After getting caught in a big rainstorm, the tach itself showed comdensation behind the lens amd my digital display (in the tach) started intermittently showing "NO DATA." Soon thereafter, it went blank and then my gauges stopped working entirely. I disconnected just this gauge and then all others started working again. Plugged it back in and the rest stopped working.

One other thing I stumbled upon purely by accident was that when I pressed and held the Display Selector rocker switch in the down position, the entire gauge set seemed to run through some kind of self diagnostic routine. First they all rotated in unison to 1/2 way point, paused, then to full point, back to zero, half, full and back. Looked kind of cool!

08-21-2013, 10:14 PM
24 pin / MMCD-IN Harness 10 pin / MMCD - Out Harness

In harness Out harness
Pin Function Pin Function
1 prim. Calibration a AIB_DATA
2 second Calibration b 7V +
3 LCD control c 7V ground
4 Cruise on/off switch d Battery Ground
5 not used e 12 V to batt +
6 not used f Ignation (12 v+ when ignation turned on)
7 lake temp g not used
8 not used h not used
9 not used I Can Shield
10 not used J DIB_
11 not used k DIB_CANH
12 Buzzer contol
13 air temp
14 Cruise +/- switch
15 RPM/SPEED Selector Switch
16 not used
17 not used
18 Ballast level
19 not used
20 not used
21 not used
22 CAN Postive
23 Can Negetive
24 Can Shield

08-21-2013, 10:37 PM
kweisner thanks for the tip. I will try both tomorrow. It would be nice if it is that easy of a fix.
I tried to post picture I of MMDC wireing, but could not get it to upload. The text got all messed up when I pasted it. I will try again tomorrow.

08-21-2013, 10:44 PM
MMDC for 2005
This is from data I have pulled off internet and running meter. I am not sure it is 100% right, but a good starting point.

08-21-2013, 10:46 PM
From my experience, if you have good power and grounds and the harness checks out good, then it's the actual component is bad, ecm, mmdc etc. but I have no first hand experience on your particular application, just general electrical diagnose and repair.

08-21-2013, 11:06 PM
I agree with your thougt.
The dealer did also check the ECU with code reader and did not find anything. I am wondering now if it has something to do with the selector switches. I have not checked them in great detail yet, and the boat has been soaked from the recent rainstorms were having in the southeast. Maybe I will get lucky and find one switches shorted.

08-21-2013, 11:10 PM
I agree with your thougt.
The dealer did also check the ECU with code reader and did not find anything. I am wondering now if it has something to do with the selector switches. I have not checked them in great detail yet, and the boat has been soaked from the recent rainstorms were having in the southeast. Maybe I will get lucky and find one switches shorted.

Just because the ecm didn't trigger any trouble codes doesn't mean it's without faults. Those are usually the hard ones to condemn a part.

08-21-2013, 11:17 PM
True. I am dont want to pull the trigger on a new ECU or MMDC untill I am 100% sure that is where the problem is. I dont want to be stuck with a high dollar part that I dont need.
That is one advantage of takeing to MC. If they try part and it does not fix it I dont have to pay for it. I need an easy fix botten right now.

09-10-2013, 07:11 AM
In one of your post you said that new fuses were tried. Does your boat have inline fuses to the mmdc? On my 03 they are located behind the kickboard under the dash about 3 feet behind the kickboard. Do you know if your boat has these 2 fuses or not? While researching my gauge problem most wiring diagrams did not show the 2 inline fuses.

09-10-2013, 07:23 AM
I did find an inline fuse for the MMDC. I think it was a 3amp. I also, found one for the paddle wheel and one for the perfect pass (which my boat does not have). I never found a second fuse for the MMDC. Do you know where yours was located? I am pretty sure as much as my dash was torn apart it is not under/behind kick panel or under dash cluster.

09-10-2013, 04:37 PM
check out this link: http://www.mastercraft.com/teamtalk/...ad.php?t=31131
I pulled the black wire casing in from behind the kick panel and found 2 fuses. IIRC one was a 3 amp and the other a 10 amp or volt? But these fuses caused my guage problems. Visually the fuses looked fine but as soon as I replaced them my gauges started working properly.
Good Luck

Topp dawg
09-19-2013, 09:33 PM
F16driver- you have any pictures of the fuses locations? I am having same issues and can't find any fuses. Thanks in advance.

09-30-2013, 10:28 AM
F16 I have not had chance to replace fuses but will try tomorrow just to make sure that is not the problem. I have checked them with my multi meter and they did have continuity. I even pulled them out and the noticed that the gauges did not do anything (the LCD display did not work, and I think the gauges did not attempt to wind up). I don’t remember a 10amp fuse but will look again.

Topp dawg, the fuses in my boat are in two locations. All the instrument (gauge fuses) are under the dash behind the kick panel. I have found the best way to access them is by removing the subwoofer and fishing them out. On my boat there if memory serves me correctly I have the following:
3 amp MMDC fuse, not 100% sure on size
5 amp perfect pass fuse -- even though I don’t have perfect pass, not 100% sure on size
2 amd fuse for paddle wheel, not 100% sure on size but I do recall this was the smallest fuse.
And there is a relay for buzzer.
all the above is under the dash, and in engine bay area this a strip next to test port with 3 10 amp fuses, but I think these are for the fuel injection and ECU.

10-02-2013, 09:38 AM
Did you find a solution to your gauge problem? It sounds so similar to a problem I'm having now with my 02 190.

01-14-2014, 02:58 PM
I finely got my gauges working. My ECU was bad.