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Changing the Main-Relay on the RL - DIY

190K views 67 replies 45 participants last post by  ThinCrusts 
#1 · (Edited)
Recently it seems like quite a few people been having problems with the RL main-relay.
I had to take some pictures for "kry01" and figure I'd put together a DIY. Hopefully it
will help save someone a few $$.

Symptom:
The starter cranks when you turn the key but the RL will not start.

Tests:
Make sure fuel is getting up front - disconnect the lower fuel lines from the fuel filter and
turn the key. If it gas is flowing then it's probably not the main-relay nor the fuel pump.
However if gas is not flowing there is a big possibility it's the main relay (small chance it
could also be your fuel-pump).

Steps to replace the Main-Relay:

1) You might first want to disconnect one of the battery cables - just a precaution since
you're replacing an electrical part.

2) Remove the panel below the steering wheel, no tools needed its just snap-on
(see red arrows pointing to metal clips around the edges).

Helmet


Bumper Automotive exterior Auto part Vehicle



3) Disconnect the connectors from the main-relay box (black box, you might need a
flash light) and remove the relay box (black box). You might need a flat screw driver
to stick between the box and the bracket (see bracket below) The plastic clip on the
box fits into the notch in the bracket (see red arrow).

Auto part Engine Wire Fuel line Automotive engine part


This is the clip on the box that fits into the slot on the bracket.

Technology Electronic device Electronics


4) Connect the new relay and reverse steps 1-3 to put everything back together.
 

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#62 ·
Old tread but still great information. I had the same problem with my 1999 3.5 RL (79500 miles) as most described here, strong starting turn-over, not a hint of combustion.

The car was towed to an Acura dealer who replaced the fuel relay in the trunk near the fuel pump itself (part #39797-SH2-003). Not sure that part was even bad but the car ran OK for about two weeks and then the same problem again. At least the car was in my garage when it happened.

Just removed the Mitsuba 0105 Main Relay per the instructions. Touched each solder "dot" on the circuit board till it flowed, connected it just hanging below the dash and the Acura cranked right up! I will order a new relay and keep the repaired one for a spare. Now to see if I can get the new one properly installed on that damn bracket while standing on my head.

One more observation, before both instances I was feeling a little hesitation on acceleration that felt like the shift points on the transmission were a little off. I think that this was a short disruption in fuel pressure and should have been fair warning.
 
#64 ·
Alright so my 2000 3.5 RL (116k miles) suddenly stalled while driving twice so far. The first time that happened I was told by a Honda dealer (closest Acura dealer was 70+ miles away) that it's a fuel pump issue which they replaced and the problem was solved. About 2 years later (in fact yesterday) it died again on the road. Car would crank but not start. Luckily a cop was right behind me so he called a tow truck and helped me get it back home. I'll take a look at removing the main relay and checking out the connections while I order a new one just in case. Hopefully like some have said, I would be able to find a cold spot, resolder it, and should be good to go as I don't feel like renting a car to do my chores for the next 2-3 days until the new main relay shows up. Wish me luck that it's that and not the fuel pump again. Cheers
 
#65 ·
to disconnect one of the battery cables - just a precaution since
you're replacing an electrical part.
Alright so my 2000 3.5 RL (116k miles) suddenly stalled while driving twice so far. The first time that happened I was told by a Honda dealer (closest Acura dealer was 70+ miles away) that it's a fuel pump issue which they replaced and the problem was solved. About 2 years later (in fact yesterday) it died again on the road. Car would crank but not start. Luckily a cop was right behind me so he called a tow truck and helped me get it back home. I'll take a look at removing the main relay and checking out the connections while I order a new one just in case. Hopefully like some have said, I would be able to find a cold spot, resolder it, and should be good to go as I don't feel like renting a car to do my chores for the next 2-3 days until the new main relay shows up. Wish me luck that it's that and not the fuel pump again. Cheers
I might have broken some clips trying to remove the cover but here's the relay. Most connections in the middle dont look as shiny as the rest so I'll resolder those but I'm worried about that scratch in the middle (definitely wasn't something I did, the only place I used a screwdriver was to wedge the clip thats on the outside of the black box).. seems like it's barely crossing over. I think I'll have to do some continuity tests to make sure there's no short because of that.
 

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#68 ·
I'm referring to the 2000 Acura RL 3.5 Navi:

Once you get cover under the steering wheel (the plastic around the key is part of it, thats a good place to also pry from) out of the way, get on your knees on the ground right next to the drivers door with your head under the steering wheel. Now look directly to the right of the steering wheel column above you, like OP said I needed a flashlight to find it but its clamped vertically to a rail that holds it through the black plastic housing.

I believe its the only relay box in that exact position with two cables going into it. Make sure to detach those before trying to get it out though.

I might be replacing it with the new one that just got here this afternoon, but once I do I'll take some more pictures to give you a better idea on where it's at.
 
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