Gene

Start with the fuse panel. Ignition on, check for voltage at both sides of 7.5 amp "trans" fuse. If power at both sides of fuse, then check reverse light switch. If not that, then something in the wiring itself. Good luck! Gene

The more I try to read the wiring diagram, the more confused I get..... As tugalo said, it appears that connector C103 serves a lot of stuff, including the engine computer, fuel pump relay, auto trans controller, and ?power latch relay. Perhaps you can try pulling the relays, one by one, and see if any of these make a difference.... Gene

This may be connector C103, which is listed as "Engine to ECM" Disconnect a battery cable first. Then reconnect the C103. Disconnect the connector at the ECM. Reconnect battery cable and see if the current draw persists. If it is gone, then ECM may be shorted. If the draw is still there, may be a shorted wire. All of the above is assuming that this connector goes to the ECM. Gene

Good work! You're probably 90% done! Perhaps one of the guys who knows these jeeps inside and out, such as hornbrod, will reply and tell you not only just where these wires go, but what's most likely to have failed. He, and a couple other forum people, are walking encyclopedias about these jeeps. However, I'd probably just take a flashlight and roll underneath and look. I would look particularly around the exhaust pipe, and around the oxygen sensor, to see whether a wire may have gotten too close and melted into the exhaust system. You're almost there! Gene

Hi Shorbagon, Do you mean that there is a current draw of 4.35 amps? That is a HUGE current drain. I agree the alternator is the most likely suspect. If the diodes short, the alternator output will be greatly reduced, and the shorted diode will act as a short-circuit, causing the current draw. Try disconnecting all the wires to the alternator, and see if the current draw is still there. Otherwise, this is plain old electrical troubleshooting. Put a meter in place for measuring the current draw, and disconnect things one at a time, disconnect the fusible link wires, pull fuses, and so forth to isolate the pathway of the current draw. Once you have a clue, you can track it down the rest of the way. Again, though, I think the alternator is most likely. Perhaps the testing was not accurate. Good luck! Gene

Looks like it flexed itself to death, I'll bet the new one will do fine! Gene

Ironically, another thread posted a link to wiring diagram. Here's the flow of power: Battery uses a red wire to go to the starter relay. Green fusible link goes to connector D4, then red wire to ignition switch pin 3. From ignition switch, there is a brown wire, which goes to a junction point, then runs to the inside fuse box, 25 amp fuse for the blower. There's then a violet/yellow wire that goes over to the heater switch. So, in all likelihood, somewhere between the starter relay and the blower switch is the problem. Easiest point to check the voltage would be at the 25 amp fuse itself, with the engine running and blower on, check the voltage at this point. The plastic fuse actually has little cutouts where the metal tab is exposed, you can just put the tip of the voltmeter probe on this. Voltage will probably be low. Then your troubleshooting is between the starter relay and the ignition switch and the inside fuse panel. Just to be sure, you did bypass the large connector on the engine side of the firewall, connector 101, per Cruisers tips? This would be most likely place for the problem. Gene

Hi Jaime, First, we feel your pain. Things like these can be very very frustrating and time-consuming to track down. Think of electricity like water. In your house, you have a water main coming in. Then you have different pipes, leading to various faucets. If you have low water pressure at one faucet, it may be from low water pressure coming into the house, it may be a problem with the large distribution pipe in your house, or it may be a problem with smaller branch lines. Electricity is the same. You have already checked the "water main". The voltage that you read that the battery is fine. This is not a problem with your battery or alternator. You were checking these voltages with the engine idling, so the alternator was only putting out a small fraction of its total output. The "pipe" that goes to the heater motor, as well as the other accessories (linkers and wipers) that seem slow, has the problem. The "pipe" that you put in for your Hellas does not have a problem. Again, this is further evidence that the battery and alternator are not the problem. So you have to troubleshoot, step-by-step, to see where the voltage is being lost. I don't have access to a wiring diagram right now. If someone could post a link to home wiring diagram, we could go through that. However, generally speaking, the wire probably goes from the battery positive to the relay on the fender well, to the 101 connector, to the inside fuse block, to the ignition switch, to the heater switch, heater resistor, and heater blower motor. Since blinkers and wipers are affected, I doubt that it's just the heater switch or resistor circuit. I believe you said you replaced the 101 connector completely. I suspect it's somewhere related to the inside fuse panel or the ignition switch. In other words, where the "pipe" supplies the blinkers, wipers, and heater blower is where the problem exists. Again, a specific wiring diagram would be very helpful. Good luck! Gene

Hi Jaime, Two basic possibilities: 1. The system voltage is low. This would involve weak battery or weak alternator. To test this, measure voltage AT THE BATTERY POSTS when the fan motor is running. If you have low voltage at the battery posts, you have a weak battery or alternator (probably both.) I think that this is very unlikely. 2. If you have 13.5 volts or so at the battery posts when the fan is running, then you are losing voltage between the battery and the fan. Please post voltage at battery posts with fan running. Thanks. Gene

Hi everyone, Which antifreeze do you run? Prestone universal? Old style green? Or other? If old style green, where do you get it? Thanks! Gene

Hi Jaime, Do you have a volt meter? You can probably buy one for about $10, please get one of these, and don't be afraid to use it. Try to find out where the voltage is dropping. For example, check voltage right at the battery posts. Then, check at the battery terminals. If there is much difference between these readings, it would indicate corrosion where the battery terminal meets the post. Then move the negative probe to the engine block, and to the firewall, finally as close to the fan housing as you can get.. If there is a significant difference here, that would indicate a problem with one of the grounds. But if that's not the case, then move the negative probe back to the battery, and start moving the positive to different locations. Systematically checking this should give you an idea where the voltage is dropping, and then hopefully you'll be able to clean/repair the offending connector. Have the heater blower running full speed while you're doing these tests. Good luck! Gene

Hi everyone, Does it matter which direction coolant flows through the heater core? Would there be a problem just using three-quarter inch hose on both three-quarter inch fittings, and 5/8 inch hose on both 5/8 inch fittings? That would reverse coolant flow through the heater core, but I don't see that that would cause a problem. Thanks! Gene

Thanks Eagle! Gene

Hi Eagle, I'm actually wondering about the physical size of the cap. I thought caps came in several different lengths, from top to bottom of spring? Or are they pretty much universal fit? Thanks Gene

Hi everyone, I just got a Moroso radiator hose filler #63745. Which radiator cap? Stant #10331 ?? Thanks! Gene

I think this may be due to collapsed hydraulic valve lifters, which may be related to oil delivery problems.... So maybe this is a result of the (oil pressure related) problem, not the cause... Gene

Most of these that I have seen use a 24 volt coil.... Thanks Gene

Typically these are 600 watts, some as high as 1000 watts, which would be 5 to 8.5 amps. I imagine I can find a timer to handle this. Thanks Gene

Hi everyone, Thanks for the replies. Western Maryland is up in the mountains, we actually have more Western Pennsylvania/Pittsburgh area weather. Typically there will be a few nights below 0° every winter. However, the main reason I'm interested in the block heater is because I live about a mile from my work. Typically, in the winter, the engine never gets warm. Consequently, the oil picks up fuel, water, and whatever else to get contaminated very quickly. So I'm thinking of putting the block heater in, and putting it on a timer, and starting with perhaps two hours of preheating. Gene

Thanks gentlemen! How long would it take for this to heat the engine? Gene

Hi Justin, Usually a bad rod bearing gets MUCH louder when accelerating. Valve train noise will get "faster" but not louder. Pull the valve cover, if nothing looks bad then run it for a short time with the valve cover off. However, if you don't have oil pressure, it is probably not valve train. Good luck! Gene

Hi everyone, Anyone using an engine block heater? What type? If it is a "freeze plug" heater, where did you install it? Any thoughts or experiences on this would be appreciated! Thanks Gene

Hi Justin, Could you make another video while increasing engine speed, to hear what the sound does while accelerating and at higher speed? Thanks Gene

On my 88 4.0, 5 speed stick, the axle had to be dropped (lower shock bolts removed), even then it was a tight fit. Allegedly you will have more room with an automatic transmission, apparently the bellhousing is lower on a stick than auto. I'm sure more knowlegable folks will confirm or debunk this. Good luck! Gene

Hydraulic....so stop feeling guilty for never adjusting them! Gene