Electrical Maladies - Page 2 - PeachParts Mercedes-Benz Forum

sailor15015 · #16 12-24-2005, 12:33 AM

Thanks I will try that. Does the nss kill the glow plugs as well or is that another issue in itself? They were working fine right up until it all quit. I'm leaving on Sunday, headed for Arizona for a week to see my sis so it'll more than likely have to wait. I replaced the nss in my wrecked '85 two weeks before the accident so if the one in the '84 is bad I'll just use it. Thanks for all your help, and merry Christmas.

sailor15015 · #17 12-24-2005, 10:34 PM

Bump, and Merry Christmas to all of you.

FineOlBenz · #18 12-25-2005, 10:39 AM

I only read your post briefly and you say that your dash lights come on when the speedo cable is connected to the speedo head. That tells me that the engine and trans are energized. Try un plugging the alternator(inluding the main power wire), if that stops the problem it's likely a bad diode.

sailor15015 · #19 12-25-2005, 01:20 PM

Thanks I'll try that. I leave in a few hours for a week so I'm trying to do all I can now.

sailor15015 · #20 12-25-2005, 02:47 PM

Ok so I unplugged the alternator and replaced the neutral safety switch. No dice. I tested it with a volt meter and there is a steady 2.97 volts coming from the speedo cable. I have no idea what to do next. Any help or advice will be immensly appreciated. Merry Christmas.

#21 12-25-2005, 02:56 PM

Quote:

Originally Posted by sailor15015

Ok so I unplugged the alternator and replaced the neutral safety switch. No dice. I tested it with a volt meter and there is a steady 2.97 volts coming from the speedo cable. I have no idea what to do next. Any help or advice will be immensly appreciated. Merry Christmas.

If you have 3V of potential between the speedo cable and ground, I would check the ground strap between the engine and the body. Do you also have 3V between the engine block and the body?

sailor15015 · #22 12-25-2005, 03:14 PM

I tested it between the egr and the body and it was almost a volt. I don't remember the exact reading. At the junction box by the batter, the wire the shares a terminal with the violet wire to the gp relay comes from the starter, correct? It also has the 2.97 volts, enough to turn off the relay when I touch them together.

#23 12-25-2005, 03:29 PM

It sure sounds like a ground problem to me. You shouldn't have any measurable voltage between the engine block and the body. Someplace (I'm not sure exactly where on your car) there is a ground connection between the engine and the body. Recommend you find that ground connection and make sure it is intact and secure. As a test, try grounding the engine block to the body with a jumper cable and see if it helps your issues.

sailor15015 · #24 12-25-2005, 03:46 PM

I'm not sure where the grounding strap is on my '84 but on the '85 its connected to one of the bolts on the tranny bell housing. I didn't think to look on the '84 but I will. Thanks. On a side note, I made a thread a couple of weeks ago about my #14 fuse blowing on my '85 before it was wrecked. I replaced the nss and it made no difference. When I was pulling it to put it in the '84 I found the problem. Whatever wire it is that runs to the back of the tranny had worn through and almost in half and was touching the pan, creating the short that would instantly blow the fuse. When I was looking under on the '84, this same black wire had a nick in it. You could see a couple of wires through the insulation. If anyone else with a similar model is having trouble with their reverse lights, check this wire. Its a single black wire that runs to the back of the tranny.

FineOlBenz · #25 12-25-2005, 07:53 PM

If you leave the car un attended disconnect the battary. I'd sure hate to see you burn a nice car down due to a short circut. There should not be power coming from the speedo cable for sure. Is it possible that the back-up lamp switch is grounding in the tranny? Try a disconnect there. Try pulling one fuse at a time to see which circut is powering up the speedo cable. I'm real sure you won't find a fuse for the speedo cable

sailor15015 · #26 12-25-2005, 11:48 PM

I'm glad I read that. I'll be sure to disconnect the battery. I'm leaving in an hour for a 17 hour drive to AZ for a week. I just went outside and clamped a jumper cable to the EGR then to the negative post of the battery and it started!!! Halelujah!!! I guess I have a problem with a grounding strap where ever it may be. I had resigned myself to calling in a mechanic that I know when I got back but now all I have to do is either fix the exhisting ground strap or make a new one. Thanks again guys for all your help, and Happy Holidays one last time.

Palangi · #27 12-25-2005, 11:56 PM

Replace your negative battery cable.

#28 12-25-2005, 11:57 PM

Glad to hear it was something easy/cheap to fix. Sometimes those are the hardest to find. Happy Holidays!

sailor15015 · #29 01-02-2006, 01:09 AM

Ok so I'm back from vacation now and I finally got her up and running again. I added a second grounding cable from the engine to the body and that got her starting. I still had a funny gauge issue so I did what Craig did and added an extra ground wire from the cluster itself. Problems solved.

Thanks to everyone for all of your help and may you all have a happy new year.