MDC Delete

[weberj5596]

I bought a 99 Malibu Sportster LX from a wrecked car auction for a good price knowing I needed to replace one of the windows. Unfortunately after getting it on the water both Speedometers and the Tach would not work. All other gauges worked fine. After several different ideas to fix the problem, I narrowed it down to be most likely the MDC causing the problem… and they are $1000 now which was a bit of sticker shock. So I went on the hunt for other solutions. There is the MDC Delete kit from TRD but that came at a hefty price tag of about $1100. At least I knew I would be getting new gauges and GPS speedos to boot. However I was stuck on wanting something a bit cheaper so I DIY’ed it for just over $400.

 

There are a handful of threads about doing a MDC Delete but none that matched my exact scenarios/wiring/etc... I followed a thread from a different forum and took updated notes along the way. Let me know if you have any questions!

 

The gauges I purchased

GPS Speedometers - https://www.amazon.com/dp/B017QRHYQC?psc=1&ref=ppx_yo2ov_dt_b_product_details

Tach - https://www.amazon.com/dp/B0000AZ68T?psc=1&ref=ppx_yo2ov_dt_b_product_details

Oil Pressure - https://www.amazon.com/dp/B000KOVJFG?psc=1&ref=ppx_yo2ov_dt_b_product_details

Fuel - https://www.amazon.com/dp/B005HNNOPS?psc=1&ref=ppx_yo2ov_dt_b_product_details

Temp - https://www.amazon.com/dp/B0000AZ7ZR?ref=ppx_yo2ov_dt_b_product_details&th=1

Volt - https://www.amazon.com/dp/B000KOVJK6?ref=ppx_yo2ov_dt_b_product_details&th=1

 

 

 

1. Unscrew dash

2. Unplug all wires from the back of gauges

3. Unplug rocker switches

4. Unplug check engine light and hour meter

5. I used pliers to loosen nuts on the back of the gauges then finger loosened them the rest of the way.

6. I then reattached all the mounting brackets to the gauges so they don’t get lost

7. The check engine light fell out of the dash hole. Set that aside for now

8. Remove tape and tubing from larger wiring harness bundle

9. Remove the 5 pin, 18 pin, and speedo connectors from Mdc. Mine had a 1/4” bolt on the 18 pin

10. Remove the mdc (mine had 3 Phillips head screws

Mine appears bent/broken… potentially causing the gauge issue I had

11. Pull the mdc harness plugs up into the gauge area

12. Disconnect gauge harness from the boat harness.

13. Remove all tubing

14. Cut off the gauge connectors (I left a little wire incase I needed to use the connectors again… in hindsight this was not necessary and having the longer blue wire would have been a better idea)

You will now be left with 2 separate harnesses. One connected to the 5pin mdc connector and 1 connected to the boat harness connector and 18pin MDC connector

15. Cut off the 5 pin and 18 pin harness connectors (this will leave you with a bunch of stand alone wires and a bunch of wires still attached to the 9 pin connector that re-plugs into the boat

Note* Once the 5 pin harness connector is cut you will be left with 2 brown wires, a bundle of black, bundle of red/white and a bundle of yellow.

16. Remove yellow wire entirely - this is the signal wire that came from the MDC which is no longer used.

17. Remove brown wires entirely… these were for the left and right speedo adjusters (I don’t need these in my setup anymore with gps speedos)

18.Strip and crimp connectors on each dark blue wire. These will be for the backlights on the gauges. The gauges I purchased require spade connectors.

19. Butt splice the black bundle or wires to the black from the 9 pin connector. I removed a couple feed of wire here… the wiring no longer has to go down to the mdc and then back up again

20. Butt splice the bundle of red/white to the purple from the 9 pin connector. (Again I removed excess)

21. The orange wire is not used. I chose to butt splice and keep the wire incase I need it in the future. Not sure what it’s for

22. I was waiting for my gauges and ring terminals to arrive in the mail so I finished my harness using old tubing and put new tape on. Each bundle is for a single gauge. The bundle on the left is the excess unused wire from the harness (additional positives, negatives, and light wires plus the orange that I don’t know what it’s for) I did this incase I add any other gauges in the future I don’t have to rework the whole harness.

Here is what I bundled together

• Fuel - Red, black, blue, pink
• Oil pressure - Red, black, blue, light blue
• Volt - Red, black, blue
• Temp - Red, black, blue, brown
• Tach - Red, black, blue, gray
• Speedo 1 - Red, black, blue
• Speedo 2 - Red, black, blue
• Extra - all remaining wires

*Note the gps speedos recommend having a power wire straight from the battery (not keyed) but I didn’t have those in my harness so I will be using a small jumper wire to jump keyed power to the signal terminal on the speedos. All this means for me is the speedos will need to reconnect to the satellite everytime I shut down… something I will likely want to fix in the future… also as I write this wondering if the orange wires are for this purpose? I’ll check on that!

23. Install all of the gauges in the panel

24. I missed a few pictures here but I added all of the ring terminals and installed the harness on the gauges.  Note I have one gauge that has a bit of a messy splice I needed due to wires being a bit short (problem would have been avoided had I not left extra wires on the connectors I cut off earlier) I just used some random wire… do as I say not as I do!

25. Hook up the wiring harness back to the harness in the boat as well as the check engine light and hour meter

26. Reattach the dash.

*Note my speedos read 5MPH while looking for GPS Signal and then return to zero. The picture shows them during that initializing stage.

 

Overall a bit time consuming yet fairly simple task. If I could have found a new 9 pin connector that matched the boat connector I would have built a harness completely from scratch. There was barely enough wire in the harness for the light connectors and some of the signal wires. But it still worked.

Edited November 29, 2022 by weberj5596
Wording update

[shawndoggy]

great post!

[BlindSquirrel]

Great work! Now, send one of those speedos back before it's too late and replace it with perfect pass.  Best upgrade you'll ever do. But it will mess up your super clean setup. I think the gauge only comes in black. For real, great work on the delete.

Edit. They come in white too!

http://perfectpass.com/?q=displays

Edited December 1, 2022 by BlindSquirrel

[weberj5596]

18 hours ago, BlindSquirrel said:

Great work! Now, send one of those speedos back before it's too late and replace it with perfect pass.  Best upgrade you'll ever do. But it will mess up your super clean setup. I think the gauge only comes in black. For real, great work on the delete.

Edit. They come in white too!

http://perfectpass.com/?q=displays

I have debated this however my understanding is adding perfect pass is very expensive? Anyone familiar with a good thread on adding it? Does it require efi?

[Bozboat]

1 minute ago, weberj5596 said:

I have debated this however my understanding is adding perfect pass is very expensive? Anyone familiar with a good thread on adding it? Does it require efi?

it does not require EFI.  It is a servo motor that pulls on the throttle linkage against the return spring. Like everything else, PP costs.  I didn't get around to adding it for several years, but after adding it, I would not ever be without it.  Think of it as a safety issue (if that helps,). You can set your speed and keep your eyes on all the lake lice instead of the dashboard.

[BlindSquirrel]

My parents might still be married if our first Echelon had it! 

[weberj5596]

Got the boat out on the water (40 Degrees F) in Wisconsin today and pulled my brother and buddy for a quick footing run to test out the gauges. Everything works amazing except the fuel gauges is not reading accurately... probably the sending unit needing replaced ( seems like quite frequently people need to replace the fuel sender when doing the MDC delete for whatever reason... But im happy with the results!

(yes that is ice on the banks)

[RebesMalibu]

Wow! That looks cold. I would think their feet would get numb pretty quickly. 
 

Is your volt gauge working correctly? It looks like it shows less than 12 volts which would be a severely discharged battery. 

[martinarcher]

Get some!!  That's awesome.    We were skiing in 48 degree water with no suit not long ago breaking in my new motor but we didn't have any ice...well done!   

[Woodski]

@RebesMalibu - he's from Wisconsin, pretty sure they felt it was just the last day of summer.

@weberj5596 - nice work, and as noted Perfect Pass is one of the best 'investments' one can make.  They do have great customer service.  Does your gang spend time on skis, that is where the system really shines.  It is one of those things once you use it you wonder how you did without it.

[weberj5596]

14 minutes ago, Woodski said:

@RebesMalibu - he's from Wisconsin, pretty sure they felt it was just the last day of summer.

@weberj5596 - nice work, and as noted Perfect Pass is one of the best 'investments' one can make.  They do have great customer service.  Does your gang spend time on skis, that is where the system really shines.  It is one of those things once you use it you wonder how you did without it.

We are everything from 2 skiing 5 year olds to 360 atb to airchair and bare-footing! It’s something I want but not something I want to drop the cash on right now! I grew up in a boat without it and my brother has it in his boat! It is nice without a doubt but more of a luxury in my mind. Eventually I’ll add it I’m sure!

[weberj5596]

4 hours ago, RebesMalibu said:

Wow! That looks cold. I would think their feet would get numb pretty quickly. 
 

Is your volt gauge working correctly? It looks like it shows less than 12 volts which would be a severely discharged battery. 

Good question! Brand new battery although the key was on quite a bit for gauge testing and such. Boat fired up just fine. Not sure of the best way to test this 

[RebesMalibu]

19 hours ago, weberj5596 said:

Good question! Brand new battery although the key was on quite a bit for gauge testing and such. Boat fired up just fine. Not sure of the best way to test this 

You could use a digital multimeter to compare the actual battery voltage to the displayed voltage. 

[LakeLife23]

Does you gas gauge work?

[moviewithnotitle]

Great Job! 
In 2010, I did the MDC delete my previous 2001 MC X10. It was a bear to get all the wiring correct, but I did almost exactly what you did here. 

The gas gauge issue is that the voltage/resistance reading from the sending unit doesn't match standard gauges(the MDC did the conversion). There are some posts on the TeamTalk / MC forums by some ppl that are way more electrically savvy than I am that explain how to measure the voltage from the sending unit and put in some resistors or diodes that will correct the voltage reading to the gauge so it reads correctly. 

[weberj5596]

On 2/26/2023 at 3:17 PM, LakeLife23 said:

Does you gas gauge work?

It ‘works’ but isn’t correct

[LakeLife23]

On 3/10/2023 at 6:58 PM, weberj5596 said:

It ‘works’ but isn’t correct

You need to put in a new sending unit. The swing arm style are not as good as the newer reed switch. For a Sportster, an 8in sending unit is required. Any questions, just ask me, I am in the middle of a minor Sportster resto that stemmed from putting in a new fuel sending unit. 

[justgary]

The fuel tank and sender are probably grounded at the engine.  The sender can give poor performance when the ground connection gets cruddy.  Check and clean the connections at the tank and at the engine (both heads) before changing a sender.

[weberj5596]

On 3/12/2023 at 7:49 PM, LakeLife23 said:

You need to put in a new sending unit. The swing arm style are not as good as the newer reed switch. For a Sportster, an 8in sending unit is required. Any questions, just ask me, I am in the middle of a minor Sportster resto that stemmed from putting in a new fuel sending unit. 

I am just getting around to tearing the boat apart to try and replace the sending unit. What a pain.

anyways, my tank is 10” tall at the location of the sending unit. Wouldn’t I need at least a 9” unit to accurately read? I also see a bunch of different options mostly 0-190 ohms and 240-33. I have no idea what I need lol

[Bushmankev]

I added HydroPhase to my 01 Sunscape instead of PP. best investment ever. HydroPhase was a bit cheaper and has more memory/functionality than PP and also has great customer service. I love the dial on my HydroPhase instead of the up/down buttons on PP. your gauges look awesome. I wish I had the knowledge (balls) to delete my MDC. I’ll install your HydroPhase if you do my gauge conversion. Lol

[Bozboat]

On 4/5/2023 at 4:26 PM, weberj5596 said:

I am just getting around to tearing the boat apart to try and replace the sending unit. What a pain.

anyways, my tank is 10” tall at the location of the sending unit. Wouldn’t I need at least a 9” unit to accurately read? I also see a bunch of different options mostly 0-190 ohms and 240-33. I have no idea what I need lol

 

[weberj5596]

On 4/23/2023 at 1:26 AM, Bushmankev said:

I added HydroPhase to my 01 Sunscape instead of PP. best investment ever. HydroPhase was a bit cheaper and has more memory/functionality than PP and also has great customer service. I love the dial on my HydroPhase instead of the up/down buttons on PP. your gauges look awesome. I wish I had the knowledge (balls) to delete my MDC. I’ll install your HydroPhase if you do my gauge conversion. Lol

Did you go gps or paddlewheel version?

the mdc delete was a bit time consuming but overall very easy. I was a little overwhelmed going into it but the guide here would give you exactly what you need to do it. It’s easy!

[Bushmankev]

On 4/26/2023 at 7:06 AM, weberj5596 said:

Did you go gps or paddlewheel version?

the mdc delete was a bit time consuming but overall very easy. I was a little overwhelmed going into it but the guide here would give you exactly what you need to do it. It’s easy!

GPS version. It’s been awesome 

[PNWoke]

Me, when I think about my MTC in light of this discussion…