fords4life Posted February 6, 2018 Author Share Posted February 6, 2018 You simply cannot use a DVM on the resistance scale to check grounds on a vehicle. It will not work. At all. The current supplied by the DVM isn't even the same league as the current pulled by the components in your truck, much less that of the starter. And the resistance of the connection will change dramatically as the current flow goes up. The only way to test grounds is the voltage drop test. Gotcha. I will start going through that tonight if I have time, at least in the engine bay. One other question I forgot to ask. I can't find anywhere in the EVTM that shows or calls for a ground to the frame. Should there be one? If so, any idea where to look? Would it be a good idea to add one? Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 6, 2018 Share Posted February 6, 2018 Gotcha. I will start going through that tonight if I have time, at least in the engine bay. One other question I forgot to ask. I can't find anywhere in the EVTM that shows or calls for a ground to the frame. Should there be one? If so, any idea where to look? Would it be a good idea to add one? I have a page on grounds here: Electrical/Ground Wires. I tried to pull together what two of my EVTM's say about grounds. Hope that helps. But yes, the negative battery cable goes to the engine and then to the frame. Link to comment Share on other sites More sharing options...
85lebaront2 Posted February 6, 2018 Share Posted February 6, 2018 I have a page on grounds here: Electrical/Ground Wires. I tried to pull together what two of my EVTM's say about grounds. Hope that helps. But yes, the negative battery cable goes to the engine and then to the frame. Gary, the original setup was battery negative to frame with a "flag" out the side of the cable, then to the engine block. The body ground is from the back of the left head to the wiper motor mount bolt. Just visible to the driver's side of wiper motor. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 6, 2018 Share Posted February 6, 2018 Gary, the original setup was battery negative to frame with a "flag" out the side of the cable, then to the engine block. The body ground is from the back of the left head to the wiper motor mount bolt. Just visible to the driver's side of wiper motor. Not a real good system, on Darth, since I have gone to later wiring, I have an actual ground wire from the negative cable to the right inner fender next to the battery. This is how the 1992-97 trucks were done, and the ground on these goes directly to the lower starter bolt which is double ended so a nut holds the negative cable on. Battery cable flag to crossmember on the way to the block. My '87 has a braided strap from the drivers floor pinch weld to the front cab support, in addition to the wire from the wiper motor to the intake manifold bolt. Link to comment Share on other sites More sharing options...
fords4life Posted February 6, 2018 Author Share Posted February 6, 2018 Battery cable flag to crossmember on the way to the block. My '87 has a braided strap from the drivers floor pinch weld to the front cab support, in addition to the wire from the wiper motor to the intake manifold bolt. It took me awhile but I finally figured out what you guys meant by "flag". I do have one to the frame, but for the life of me I could not get any continuity from the frame to the negative side of the cable or any grounds. Starting to wonder if that cable is bad. I know the insulation around the flag is in bad shape. There aren't very many places that carry the cable with the flag and even fewer that have it in stock..... Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 6, 2018 Share Posted February 6, 2018 It took me awhile but I finally figured out what you guys meant by "flag". I do have one to the frame, but for the life of me I could not get any continuity from the frame to the negative side of the cable or any grounds. Starting to wonder if that cable is bad. I know the insulation around the flag is in bad shape. There aren't very many places that carry the cable with the flag and even fewer that have it in stock..... It is fine to have two cables, one from the battery to the engine and one from the engine to the frame, and connect them at the engine. I suspect that Ford used the one-piece cable to ease installation rather than because it works better - although there is one less "connection" that way so it should work good longer. But you can test your grounds pretty easily with the voltage-drop test. Link to comment Share on other sites More sharing options...
85lebaront2 Posted February 6, 2018 Share Posted February 6, 2018 It is fine to have two cables, one from the battery to the engine and one from the engine to the frame, and connect them at the engine. I suspect that Ford used the one-piece cable to ease installation rather than because it works better - although there is one less "connection" that way so it should work good longer. But you can test your grounds pretty easily with the voltage-drop test. What Gary is suggesting is exactly what I did on Darth. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 6, 2018 Share Posted February 6, 2018 Still fighting this darn thing. Replaced the hot side batter cable and starter relay because both about fell apart when I touched them. The ground on the drivers side front fender was a little loose, tightened it up and seemed to help make the headlights a bit brighter. Check the ground from the battery to the engine I'm getting less than 1ohm. From passenger side engine to drivers side back of engine I'm at 1.1ohms. From Drivers side back of engine to firewall I was right around 1ohm IIRC. From Firewall to fender was 1.8ohms. Haven't checked anything from the engine bay to the back of the truck yet. Had lights working one time the other night and then I started it, lights are not working again. Also found out the rear tank fuel pump/sending unit or the switch on the dash are not working. Haven't had a chance to start diagnosing this one yet. Will try to post a couple pictures tonight of an interesting power(assuming) connection under the dash. There are 5 or 6 red wires all connected together via a bolt under the instrument cluster. Finally broke down and ordered a Power Probe so I can start isolation and testing individual components and separate sections of harness to test. Hopefully it will help to narrow down where the problem is. Anyone have a good place for purchasing OEM style electrical connectors? I'd like to start replacing sections of the harness as I can but would like to use OEM style plugs without paying Ford's price. I will third the suggestion of using two cables. A large gauge battery cable to the block and something like 6 Ga. from block to frame is fine. My negative cable has a smaller wire incorporated into the battery clamp that goes to the radiator support like Bill's does. Though I don't 'need' a computer ground there I'm sure it helps with the headlight grounding on my relay system. If you want OEM connectors the entire Motorcraft plug and pigtail catalog is available as a pdf online. I can't link it, because my phone will automatically download it from the url, and then I have to delete it (again and again) Find the connector you need and do a web search for the number. Pricing through Ford is ridiculous. They will pop up on Ebay or Amazon. Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 6, 2018 Share Posted February 6, 2018 I will third the suggestion of using two cables. A large gauge battery cable to the block and something like 6 Ga. from block to frame is fine. My negative cable has a smaller wire incorporated into the battery clamp that goes to the radiator support like Bill's does. Though I don't 'need' a computer ground there I'm sure it helps with the headlight grounding on my relay system. If you want OEM connectors the entire Motorcraft plug and pigtail catalog is available as a pdf online. I can't link it, because my phone will automatically download it from the url, and then I have to delete it (again and again) Find the connector you need and do a web search for the number. Pricing through Ford is ridiculous. They will pop up on Ebay or Amazon. I have links to the catalog under Electrical/Wiring Connectors. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 6, 2018 Share Posted February 6, 2018 I have links to the catalog under Electrical/Wiring Connectors. I should have known. But I didn't see the question addressed so I thought I should mention it. Link to comment Share on other sites More sharing options...
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