ArdWrknTrk Posted May 21, 2020 Share Posted May 21, 2020 And as for that page from the 1986 EVTM, my truck is an EEC-IV, not a Duraspark. Does that make any difference? So, let's look at those pages... I see a resistor in line before the dg/y goes into the ECA, but I don't see a tach output. Was the EEC 4.9 never available with a tach? Link to comment Share on other sites More sharing options...
thefraze_1020 Posted May 21, 2020 Author Share Posted May 21, 2020 So, let's look at those pages... I see a resistor in line before the dg/y goes into the ECA, but I don't see a tach output. Was the EEC 4.9 never available with a tach? Well if that is the case, that would be one (unfortunate) answer to why my tach doesn't work. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted May 21, 2020 Share Posted May 21, 2020 Well if that is the case, that would be one (unfortunate) answer to why my tach doesn't work. I honestly don't know Cam. We should get Dave (Fuzzface) or David on the case because it surely seems unlikely that a tach wasnt an option on your truck. I'm only looking at the diagram shown in the EVTM, but they deal with specific circuits, not the whole thing. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted May 21, 2020 Share Posted May 21, 2020 I honestly don't know Cam. We should get Dave (Fuzzface) or David on the case because it surely seems unlikely that a tach wasnt an option on your truck. I'm only looking at the diagram shown in the EVTM, but they deal with specific circuits, not the whole thing. I'm a dumbass. It's right there on the first page pointing straight up, wire 11 (see pg 95) 640 r/y hot in run. Lower left 60 bk/lg (ground) Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted May 21, 2020 Share Posted May 21, 2020 I'm a dumbass. It's right there on the first page pointing straight up, wire 11 (see pg 95) 640 r/y hot in run. Lower left 60 bk/lg (ground) Sorry It's hard to do this on a phone. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted May 21, 2020 Share Posted May 21, 2020 I honestly don't know Cam. We should get Dave (Fuzzface) or David on the case because it surely seems unlikely that a tach wasnt an option on your truck. I'm only looking at the diagram shown in the EVTM, but they deal with specific circuits, not the whole thing. Good you found it as I don't know how much help I would have been. My truck is an 81 with a 300 six and all I had to do was swap in the tach gauge cluster and it worked. So if anything had to be done at the ICM area to get the tach to work I did not need to do. Yea looking at the wiring on a phone can be hair pulling Dave ---- Link to comment Share on other sites More sharing options...
Sac79 Posted May 21, 2020 Share Posted May 21, 2020 I honestly don't know Cam. We should get Dave (Fuzzface) or David on the case because it surely seems unlikely that a tach wasnt an option on your truck. I'm only looking at the diagram shown in the EVTM, but they deal with specific circuits, not the whole thing. Good you found it as I don't know how much help I would have been. My truck is an 81 with a 300 six and all I had to do was swap in the tach gauge cluster and it worked. So if anything had to be done at the ICM area to get the tach to work I did not need to do. Yea looking at the wiring on a phone can be hair pulling Dave ---- I swapped in a tach cluster and did not have to do anything either. And I had EEC. Not sure if it will work now with the HEI, I'm hoping so. Here's a pic for reference. All the nuts are tight. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted May 21, 2020 Share Posted May 21, 2020 I swapped in a tach cluster and did not have to do anything either. And I had EEC. Not sure if it will work now with the HEI, I'm hoping so. Here's a pic for reference. All the nuts are tight. I think it should be easy enough to 'prove' ground, key on power and that the all important tach pulse wire is good all the way to the coil. There are only a few connectors that might be corroded. (easy to check, and clean) At least we can follow the whole circuit now. If all that works it must be the tach. Link to comment Share on other sites More sharing options...
Gary Lewis Posted May 21, 2020 Share Posted May 21, 2020 I think it should be easy enough to 'prove' ground, key on power and that the all important tach pulse wire is good all the way to the coil. There are only a few connectors that might be corroded. (easy to check, and clean) At least we can follow the whole circuit now. If all that works it must be the tach. There's only one more connector, C169, and it is said to be a brown 2-pin near the fuel pump relay, meaning on the driver's side of the firewall between the brake booster and fender. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted May 21, 2020 Share Posted May 21, 2020 There's only one more connector, C169, and it is said to be a brown 2-pin near the fuel pump relay, meaning on the driver's side of the firewall between the brake booster and fender. It's shown on pg 95 (above) which seems to be the correct page for a 4.9 w/EEC Which EVTM are you using Gary? Is it on this site? Maybe I missed it Link to comment Share on other sites More sharing options...
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