RE: Main Contactor Ohm reading across coil leads

Hi, wondering if you could give me an assist?
I have a 2000 e825 that is giving me fits. My contactor won’t engage. If I push it in, it stays in until I turn off the key. I have power (73-76Vdc)to it. If I take the black wire that goes to the controller off, then ground the contactor coil terminal to B-, it engages. I have continuity thru the black wire from contactor to controller. Coil reads 117 Ohms, spec says it should draw 0.6 amps with continuous use, so that works out about right. I don’t know if the coil is bad or it isn’t receiving an adequate ground from the controller. This issue came up after the car sat for about 2 months. Worked fine before. Batteries are fully charged and giving me about 76 volts.

Any ideas or info would be greatly appreciated!
Thanks,
Dave
Galveston, Texas

Taking public for more input from the forum.
Test voltage across coil when it should be engaging.
Then test after it is latched in.
Does car run ok when contactor is in?
Any error codes?

Thanks for responding. I’ll reinstall everything and check those voltages, was getting error code 51. Didn’t actually try to move the car when I pushed the contactor in manually, will see what it does. Am cleaning all the terminals above and below the controller right now.

That’s different!
No pre-charge. Check voltage on P1. Fu3 fuse ok?
If P1 is at B+ and P2 at B+ with key then controller is bad.
Might be a work around if car runs, or battery might just be low.

In step 8 of electrical troubleshooting chapter 5, page 9 (thanks to old houseboater) black wire to contactor has 76 volts key on, 0 volts key off, then 76 volts key back on again (indicates contactor bad?). Car does not run when contactor manually engaged. P1 76 volts, P1 and P2 76 volts key on. Apparently, all critical inputs for contactor operation are good. I guess cheaper to order a new contactor than a controller to start with. Don’t understand why it doesn’t run when contactor manually engaged?

If contactor holds in it must be good.
Do the tests above.

Just found a blown 1/2 amp fuse in the PWB. Had to order fuses for it. Other PWB fuse is ok.

1/2 amp fuse blew immediately. In previous post you mentioned Fu3 fuse. Is that the 400 amp? if so, its good.

Fuse blew on install? Is the car still powered up(key on)?

This is a fuse on the PWB? Or a random one inline on a wire?
(Thinking out loud)1/2a will not be used to power much of a load. Whatever it protects is not high current.

Let’s review some facts here…

If I push it in(contactor), it stays in until I turn off the key.

Does it still do this? This is real odd behavior.


Is it still throwing any codes?

Finally got back to this project. So I think the controller failed initially. Put in new T2 controller, but then the key would not turn off the car, stayed on all the time. Seemed the controller toasted the ign relay inside the dc converter. Bought a used Surepower with adapter harness from Ride4Fun. Key turns car on and off, car drives fine but no 12Vdc power. Seems to be grounding out and shutting down the converter. Just ordered a dc clamp on meter and will start trying to find the problem. I bench tested the converted up to about 10 amps, works fine. Car has DeltaQ charger. Does anyone have a wiring diagram that shows how that works with the interlock? Any ideas where I should start with this mess?

It’s not throwing any codes…

SUCCESS! Thanks to MikeKC’s post from several years ago. He posted Polaris’ installation instructions for the Surepower converter. Complete wiring diagram. The three different available onboard chargers all require a slightly different interlock configuration. I hope he will repost the link, or with his permission, I will.

Thanks to all the feedback from you guys to help me solve this problem.

Nice. Wow! Your final solution sure took a tour of components before your car settled back to stable running condition. It just goes to show people how complex and integrated the systems are and sometimes there is no simple solution to “why is my car not running?”. Your last post has a few other highlights.

As you found out, it is not such a simple thing to do the DC Converter recall/update. It is not a plug it in and go simple fix. Even your T1 to T2 motor controller swap needs a few wires moved around and updated.

And you have discovered the value of the archives. New members usually miss that the search tool can be used to page more than two decades of other posts from people that may have an issue such as yours.

[golf clap] :clap:
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