ParadiseMJ Posted February 7, 2015 Share Posted February 7, 2015 So I've sorted out the voltage drop with my lights, installing a headlight harness and a new switch and have nice bright lights (stock) with zero v drop. However, now, when I turn on my blower for heat, the volt meter drops like a rock to <9 v. Can anyone tell me why...and how to fix? The blower works as it should on all speeds without any (except this issue) problems. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 7, 2015 Share Posted February 7, 2015 Mine does too, been that way for three years now, and will continue to be that way. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted February 7, 2015 Share Posted February 7, 2015 Check the voltage at the battery with a multimeter . My gauge does not reflect the true voltage . Link to comment Share on other sites More sharing options...
ParadiseMJ Posted February 7, 2015 Author Share Posted February 7, 2015 Yes, that's the bitsch of it. The battery voltage is fine under the hood...just not at the gauge. Can anyone tell me where the gauge picks up it's info...is there a specific place where the voltage (for the gauge) reading can be going south? Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted February 7, 2015 Share Posted February 7, 2015 We are both in the same boat lol. I posted the same question and Hornbrod also is in the same boat as me and said not to worry about it . I hate wiring and maybe someone with good wiring experience may be able to help. Link to comment Share on other sites More sharing options...
reubj Posted February 7, 2015 Share Posted February 7, 2015 I believe the guage is connected to the fuse block. For the most accurate reading the connection should possibly be made directly to the battery terminal. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 8, 2015 Share Posted February 8, 2015 ^^ This. Had the same problem on the headlamp and dual electric fan circuits, and traced the voltmeter + sensing lead back to the PDC fuse block using the FSM wiring diagram. Removed it, and rerouted it to the big positive mains cable that feeds the PDC. Now it doesn't fluctuate at all. Of course it's wired differently on a Renix, buy you can do the same thing. I want the VM to read the overall state of the battery, not drop or flicker whenever it sees a load. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 8, 2015 Share Posted February 8, 2015 My lights and fan are powered through relays at the battery, not the fuse block. The heater fan is powered at the fuse block. The gauge is reading the load on the fuse block, that's it, nothing more, as to the cause of fluctuation. Link to comment Share on other sites More sharing options...
Rockfrog Posted February 8, 2015 Share Posted February 8, 2015 Good to know, my 88 Guage has never given me battery voltage, always way low. Tested the battery engine off and on and all was fine. But looking at the gauge you'd think the battery or alt was done for. Time to do some light reading on rerouting the Renix gauge lead. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted February 8, 2015 Author Share Posted February 8, 2015 So on my rig...the Renix...could I expect to see the sensing wire on the big chrome starter relay that has all the fusible links etc.? Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 8, 2015 Share Posted February 8, 2015 Here- http://www.jeepforum.com/forum/f11/renix-voltage-gauge-fix-684375/ It's easier to let someone else explain it. :) Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 8, 2015 Share Posted February 8, 2015 Repeat - look in the Electrical FSM that corresponds to the year of your rig. If you don't have the Electrical FSM for your rig, get one. Using the FSM wiring diagram, trace the VM + sensing lead out to it's source, remove it from that source, and run a new lead from that point to the nearest location that's the electrical equivalent of the battery positive terminal. Running a new sensing lead all the way to the VM input terminal is, uh, dumb. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 8, 2015 Share Posted February 8, 2015 Repeat - look in the Electrical FSM that corresponds to the year of your rig. If you don't have the Electrical FSM for your rig, get one. Using the FSM wiring diagram, trace the VM + sensing lead out to it's source, remove it from that source, and run a new lead from that point to the nearest location that's the electrical equivalent of the battery positive terminal. Running a new sensing lead all the way to the VM input terminal is, uh, dumb. The cluster has a power source from the FB, this is where the VM reads from. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 8, 2015 Share Posted February 8, 2015 Not so with the HOs. But since I don't have a Renix FSM Electrical manual, I'll take your word for that. Oh wait, I do, here: https://onedrive.live.com/?cid=c40904cfda278a46&id=C40904CFDA278A46!115 Thanks, I'll check it out. Link to comment Share on other sites More sharing options...
Rockfrog Posted February 9, 2015 Share Posted February 9, 2015 Looks like the Renix voltage reading flows from the alternator light lead, what this means for what the Guage reads? Dunno, but it isn't reading charging voltage like the HO's do (or at least my 00 does). Which is what I want it to do. Link to comment Share on other sites More sharing options...
Zebvance Posted February 9, 2015 Share Posted February 9, 2015 I also have the same problem Link to comment Share on other sites More sharing options...
cruiser54 Posted February 10, 2015 Share Posted February 10, 2015 More than likely there is resistance in a connector between the alternator and gauge. Have you guys with Renixes done the instrument panel ground upgrade? Certainly worthwhile. Tip 18 in my signature link. From the alternator, voItage travels through the C335 connector, a one wire round connector behind the battery, through the C100 connector under the brake booster, to the instrument panel. Also, be aware that the blower motor grounds under one of those chintzy sheet metal screws on the driver's side inner fender. Clean those up and make sure they're secure. Link to comment Share on other sites More sharing options...
Zebvance Posted February 10, 2015 Share Posted February 10, 2015 I have done your tip when I was replacing a bad headlight switch cruiser. Looked like it helped make the cluster a little brighter but not the voltage drop. Thanks for being a valuable member on the cc/cherokee forum btw. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 10, 2015 Share Posted February 10, 2015 So, everybody has the gauge drop with the blower motor on then? Link to comment Share on other sites More sharing options...
Rockfrog Posted February 10, 2015 Share Posted February 10, 2015 Generally my Guage reads about 10v ... But I usually leave the blower on all the time anyway. Occasionally it will read 12v-ish and once in a blue moon it will read almost 14v. I've tested battery voltage and alt output, all well within spec on the high side. 12.4 batt, 14.2 charging ... Starter never lags, and she always fires right up (well as right up as a Renix gets, quicker since the 2.8L TPS swap, three beats and vroom). I'd prefer it to read battery voltage once in it's life. I added a 10g high strand lead from dash brace to ground. And upgraded all the battery ground leads to 2ga, with 4ga off the head to firewall. Looking for a 90 engine harness to make eliminating the C101 easier (I'm weird like that). I do have an 88 XJ interior/dash harness (that actually looks damn near new) I will one day swap in as my fuse box has been worked over by the previous owner. But, that's a task I'm not up to at the moment. My headlights have been relayed and the header harness rewired with a new 97+ harness so no real load from that side either (gauge barely even moves when I hit the headlights now. I do know I'm only getting around 5v through the clock circuit lead now, but that fuse box connection looks like the PO chewed on it for a while, then hammered back. Must be "a jeep thing ... hell if I understand" ... Link to comment Share on other sites More sharing options...
Dillithium Posted February 10, 2015 Share Posted February 10, 2015 So, everybody has the gauge drop with the blower motor on then? Nope, my gauge will move left but no more than 0.2 to 0.6 volt, depending on high or low setting. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 10, 2015 Share Posted February 10, 2015 So, everybody has the gauge drop with the blower motor on then? Nope, my gauge will move left but no more than 0.2 to 0.6 volt, depending on high or low setting. Should have been clearer in my post. Everybody having the major drop in voltmeter reading has it when the blower is turned on? Link to comment Share on other sites More sharing options...
Akula69 Posted February 10, 2015 Share Posted February 10, 2015 Did have this problem (major voltage drop) on the 89 (now 99). In the 89, it centered on the ignition switch. Even after going through the entire harness and upgrading grounds, replacing power leads from the battery the ignition switch is apparently the weak link in the dash electronics harness, as almost all of the voltage for the dash moves through the switch. In some cases I have even seen the plugs and/or switch partially melted together due to the resistance. After the upgrade to the 99 dash and electronics I noticed the draw was still major when the blower is switched on - after some research found the age of the blower motor and resistor seemed to have a lot to do with it. Replaced the blower - and the excessive draw stopped. Aged windings...weak magnets...you want to weigh in here Don? Link to comment Share on other sites More sharing options...
cruiser54 Posted February 10, 2015 Share Posted February 10, 2015 Did have this problem (major voltage drop) on the 89 (now 99). In the 89, it centered on the ignition switch. Even after going through the entire harness and upgrading grounds, replacing power leads from the battery the ignition switch is apparently the weak link in the dash electronics harness, as almost all of the voltage for the dash moves through the switch. In some cases I have even seen the plugs and/or switch partially melted together due to the resistance. After the upgrade to the 99 dash and electronics I noticed the draw was still major when the blower is switched on - after some research found the age of the blower motor and resistor seemed to have a lot to do with it. Replaced the blower - and the excessive draw stopped. Aged windings...weak magnets...you want to weigh in here Don? Interesting, as that big brown wire off the switch that melts frequently.....powers the blower motor!!! Link to comment Share on other sites More sharing options...
ParadiseMJ Posted February 10, 2015 Author Share Posted February 10, 2015 I'll have to stick my head under there and check the brown wire. I'm getting a bit more comfortable with wiring after making my own headlight harness (which is awesome, even with my stock lights). Link to comment Share on other sites More sharing options...
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