Patrik 3 Posted January 9 Hi I really need your help with this odd electric issue. I have spent a lot of time searching for similar problem without success. When I turn the key, front light and display back light works fine, no data on the display and no noise from fuelpump. I have 12v on all fuses except ignition fuse, if I just quickly connect a wire direct from battery + to the top of the ignition fuse the display work as normal and I hear the buzzing sound from fuelpump. Just by quickly touching the top of the ignition fuse with the hot wire, power comes on and stays on. When this is done I can start and everything works perfect. Any ideas? Thanks in advance! Share this post Link to post Share on other sites
jeepwm69 7,619 Posted January 9 First thing I'd do is see if that fuse is hot on one side, and not the other (use a test light). Sometimes a fuse will connect on one side, but the connector gets pushed down in the fuse box, and the other side doesn't make the connection. If that doesn't work, you might have a bad fuel pump relay, or a bank angle/ flip over sensor. Remove the fuel pump relay, tap it on something, and plug it back in. See if that works. You can bypass the bank angle sensor by unplugging it and putting a jumper into the wiring harness side of the connector (paper clip, for example). @retro @Melatv and @AKATV seem to be the best at the electrical gremlins on here. My recommendation is based on things I've had them help me with over the years. Share this post Link to post Share on other sites
Patrik 3 Posted January 9 Thanks for your input! I have no power coming to the ignition fuse, that is tested. Checked continuity from key switch to ignition fuse and there are continuity when battery is disconnected. wire harness, ecu, relays and bank angle sensor is brand new. Share this post Link to post Share on other sites
jeepwm69 7,619 Posted January 10 Switch OEM or aftermarket? Looks like if you have continuity from switch to ign fuse, then the switch might be bad. You could try shaving a bit of insulation off the wires going to ignition switch and use a jumper wire to see if you get power that way. If so, bad switch. 1 Share this post Link to post Share on other sites
Patrik 3 Posted January 10 I have checked continuity in the key switch as well and it looks good, since head lights are working I assume I have power to the switch. Its odd that power to ignition fuse is constant after just touching the top of the fuse with a hot wire. It feels more like its a signal that is cutting power. The only thing that is new AM is the fuel pump & engine stop relays, I have switched them but could both of them be bad right out the box? Share this post Link to post Share on other sites
jeepwm69 7,619 Posted January 10 Just now, Patrik said: I have checked continuity in the key switch as well and it looks good, since head lights are working I assume I have power to the switch. Its odd that power to ignition fuse is constant after just touching the top of the fuse with a hot wire. It feels more like its a signal that is cutting power. The only thing that is new AM is the fuel pump & engine stop relays, I have switched them but could both of them be bad right out the box? Did you use OEM parts on the relay etc? Share this post Link to post Share on other sites
Patrik 3 Posted January 10 Engine stop relay & fuel pump relay are after market or do you have the solenoid in mind? The solenoid was on the bike when I bought it so I don't now if its OEM but the solenoid shouldn't effect the ignition power as long as you don't push the start button? Share this post Link to post Share on other sites
jeepwm69 7,619 Posted January 10 Aren't the engine stop relay and fuel pump relay together in the same part? My guess is the fuel pump relay is the problem. These Hondas do not work well, if at all, with aftermarket china electrical crap on them. Get an OEM relay and see if that fixes your problem. You'll see a similar issue here in this recent thread which is still ongoing, and I've got a 2012 Foreman in my yard which is also having ignition issues, which I suspect are caused by aftermarket electrical stuff being put on in an attempt to troubleshoot a no-spark issue. 2010 Honda Rancher 420TEA ignition fuse issue. - Electronics - ATV Honda Share this post Link to post Share on other sites
jeepwm69 7,619 Posted January 10 @retro @Melatv anything to add? Share this post Link to post Share on other sites
Patrik 3 Posted January 10 I have the model with pull start so I have 2, #15 on the picture Share this post Link to post Share on other sites
jeepwm69 7,619 Posted January 10 Huh.....well that's new. I knew the 420's had a pull start in Canada, but didn't realize you had a 2nd relay back there. I thought it was just a capacitor and the recoil itself. Do you have your old OEM relays? Share this post Link to post Share on other sites
Patrik 3 Posted January 10 I live in Sweden so I assume we got the same version as in Canada. I bought this atv as a project a couple of months ago. Same thing with the old relays but don’t know if they are oem but I assume they are. Share this post Link to post Share on other sites
retro 4,048 Posted January 11 Hi Patrik, First thing you'll need to do is put all of the genuine Honda parts back on your Rancher. Then remove the front fender, unplug the ignition switch and test for continuity with the switch turned OFF then turned ON, as shown here: I agree with @jeepwm69, it sounds to me like your Ignition switch is bad. The Ignition switch controls two positive battery voltage circuits. Make sure that both circuits are switched ON and OFF properly. You'll be checking for continuity between the Red/Black and Pink terminals and again between the Red and Black terminals inside the switch connector. Here is the Ignition circuits diagram. As you can see positive battery voltage must pass through the Ignition switch in order to reach the 10 amps Ignition fuse. If you need a new Ignition switch make sure that the replacement is a genuine Honda switch. China aftermarket parts are garbage and do not ever work on a Honda. China parts destroy other expensive parts, never plug any aftermarket part in. I'll be unavailable for a few days... I'll be back as soon as I can. Let us know how it goes. Share this post Link to post Share on other sites
Patrik 3 Posted January 11 Thanks for your input, I really appreciate all possible help! All plastics are taken off so its easy to reach all parts. I have already tested the continuity in the key switch and it tested ok but I will do it one more time just to double check. The ignition circuit diagram is quite simple and that's why this is so frustrating. If I have power to the key switch and the switch is ok, is it something else that could cut power to ignition fuse? It doesn´t look that way in the diagram. Lets say that the engine stop relay is bad, wouldnt I still have power to the ignition fuse? Both the PCM/ECM & bank angle sensor is new OEM parts Share this post Link to post Share on other sites
shadetree 5,884 Posted January 11 2 hours ago, Patrik said: Thanks for your input, I really appreciate all possible help! All plastics are taken off so its easy to reach all parts. I have already tested the continuity in the key switch and it tested ok but I will do it one more time just to double check. The ignition circuit diagram is quite simple and that's why this is so frustrating. If I have power to the key switch and the switch is ok, is it something else that could cut power to ignition fuse? It doesn´t look that way in the diagram. Lets say that the engine stop relay is bad, wouldnt I still have power to the ignition fuse? Both the PCM/ECM & bank angle sensor is new OEM parts next time you lose power to ignition switch, try probing under the fuse box, wire leading to fuse, i have heard of bad fuse boxes from the factory being defective from the factory. keep in mind, most ignition fuses get their power straight from the battery. also, check your battery to ground connection..make sure its clean and tight ?. Share this post Link to post Share on other sites
jeepwm69 7,619 Posted January 11 6 hours ago, Patrik said: Thanks for your input, I really appreciate all possible help! All plastics are taken off so its easy to reach all parts. I have already tested the continuity in the key switch and it tested ok but I will do it one more time just to double check. The ignition circuit diagram is quite simple and that's why this is so frustrating. If I have power to the key switch and the switch is ok, is it something else that could cut power to ignition fuse? It doesn´t look that way in the diagram. Lets say that the engine stop relay is bad, wouldnt I still have power to the ignition fuse? Both the PCM/ECM & bank angle sensor is new OEM parts I'd check for power going into and out of the EFI and Stop relay. On my 09 420 I would get power to display, but no spark with a bad EFI relay, but sounds like your machine might be a bit different with the 2nd relay, and again, no telling what you'll get with aftermarket bits. Plug the old OEM relays into your harness, and see if you get display, or if anything is different. A lot of the time, simply rapping the relays on the rack and cleaning the connections in the plug will allow them to temporarily work again. Share this post Link to post Share on other sites
Patrik 3 Posted January 11 Maybe a stupid question but where does the power goes from R/B to R? The blue circle in the picture Share this post Link to post Share on other sites
jeepwm69 7,619 Posted January 11 Perhaps where the ignition switch plugs into the main harness? Looks like there should be a R/Bl wire coming out of the main fuse. Is there also one going to the connector where the ignition switch plugs into the main harness? Share this post Link to post Share on other sites
Patrik 3 Posted January 11 Since I don't have power in the red wire to key ignition and its connected to a few things along the way I have some searching to do! Share this post Link to post Share on other sites
retro 4,048 Posted January 11 2 hours ago, Patrik said: Maybe a stupid question but where does the power goes from R/B to R? The blue circle in the picture There are no stupid questions! Here is the wiring diagram for the Canadian version of the '08 TM/FM Rancher 420: In this wiring diagram there is a 14p connector that serves two functions: One function is a Waterproof junction where the Red/Black wire going in to the junction becomes a Red wire coming out of that junction. This diagram may be different from your version since this one shows the Engine Stop relay and the Fuel Pump relay unified as a single relays module, whereas your version has two separate relays. But somewhere nearby the two relays on your Rancher there should be a junction connector, OR the wire junctions may be included in your two relay connectors? Look for the relevant wire colors that could identify those wire junctions (R/Bl, R, W/Bl) going into and coming out of that/those connector(s). If I were you I would not plug those two aftermarket relays in again. Test your two OEM relays, they are probably both good. China relays are known to stick and fry other expensive components, often immediately after plugging them in. 17 minutes ago, Patrik said: Since I don't have power in the red wire to key ignition and its connected to a few things along the way I have some searching to do! Yeah hopefully you'll find the open circuit issue in the Junction connector(s). Gotta run.... this is fun! Hang in there! Share this post Link to post Share on other sites
Patrik 3 Posted January 11 Appreciate the support and yes its a bit fun:-) Trying to find the correct wiring diagram, so if any one have or find the diagram with 2 separate relays I would appreciate it! TRX 420 2008 FM with pull start. Share this post Link to post Share on other sites
Melatv 792 Posted January 11 Hi: I don't think you will find a print -- it was a add on later - this may help 1 Share this post Link to post Share on other sites
Melatv 792 Posted January 11 Also disconnect the Ign. switch and check the continuity with the switch closed between the R and black wires Share this post Link to post Share on other sites
Patrik 3 Posted January 12 I have now checked continuity from main fuse to red wire on key switch, it goes from R/B on main fuse thru the 14p connector ( the one that goes to the 2 relays). Continuity is OK I measured the voltage at the key switch and now R/BL shows 12,5v, the red shows 7,5v, power disappear somewhere. I have ordered new OEM relays just to be able to exclude them. Battery is good, I have 2 new ones and tested both with a winch Share this post Link to post Share on other sites
Melatv 792 Posted January 12 Hi: Like I said above disconnect the KEY Switch and measure the resistance across the red & Black wires -- should read zero -- I have replaced a few key switches on the 420 Hondas Share this post Link to post Share on other sites
