Originally Posted by Jmh2fb
Hi, new user and new owner of 78 cj7. First jeep and love the vehicle--the wiring is another story. Jeeps runs great and has lots of upgrades including efi.
1. Have noticed two issues: battery drains at night and after running around town 30 mins two nights in a row,
2. the headlights will cycle on and off for a few min then operate fine.
1. You need FIX what PO has done.
The smaller 'Red' wire to the battery needs to be attached to the battery cable side of the starter relay.
That wire MUST go to the 'Brass' post on the breaker,
And the 'Silver' or 'Steel' post on the breaker goes out to the accessory.
I can't tell in the picture if it's wired this way or not.
You need to DISCONNECT either the positive or negative battery cable from the battery, and put a volt meter between cable and post.
This will let you track voltage drawn from battery with the key switch 'OFF'.
Start pulling fuses, disconnecting things until you find the drain,
Then address the drain issues.
Where I would start,
There *Should* be two wires (About 10 Ga.) connected to the starter relay battery cable post.
One should be the alternator 'BAT' terminal,
The other should be the feed to the headlights/fuse block.
This will tell you right away if the drain is under the dash or the alternator.
When alternator rectifiers fail, they drain batteries. Disconnecting a bad alternator will show you a significant drop in 'Drain' on the battery,
And the same is true when you disconnect the power feed to headlights and fuse block under the dash.
This will give you a direction to go with further testing...
2. Headlights draw power from the same 10 Ga. wire that powers the fuse block,
BUT ARE NOT connected to the fuse block.
All other lights have a fuse, but headlights have their own circuit breaker built into the headlight switch.
The 'ON/OFF' cycling of the headlights might be that breaker in the switch giving up,
Or it might be your headlights are drawing more current than the breaker can supply safely and the SELF RESETTING breaker is cycling to save your wiring...
If that is the case, there is probably a bad dimmer switch, pinched wire, over sized lights, ect. causing the breaker to cycle and save the wiring.
You can see there are extra relays but a few questions since posts say not to have anything directly to positive battery terminal. You can see former owner has added a relay for the efi that is connected directly to positive terminal and to alt.
Like I said, move the battery small wire connection to the starter relay, battery cable side,
And treat it like a third point of drain,
Unhook it with volt meter connected between battery post and cable to see if it's sucking your battery while the key switch is 'Off'...
A few dumb (likely) questions:
Q1: starter only has one wire to solenoid (far side) and no connection to the negative battery post, is that correct?
Starter relay depends on *IF*...
You have an automatic transmission or not.
Automatics have an isolated 'Ground' to the solenoid that is routed through the Neutral Safety Switch.
Not in 'Neutral' or 'Park', the engine won't crank.
Manual transmission starter relays don't have that isolated 'Ground' and connect to Battery Negative through the sheet metal.
An added dedicated 'Ground' to the bracket always helps with diagnostics and with starting, and isn't a bad idea if you are wiring anyway...
Q2: new alternator with main wire to solenoid and then two wires combined into one that goes to that extra efi relay. Correct?
Fuel injection computers can be incredibly picky about 'Line Voltage'!
NO WIRE SHOULD GO TO THE ALTERNATOR 'BAT' TERMINAL WITHOUT A FUSIBLE LINK OR FUSE!
You *Should* run the alternator 'Output' back to the battery cable connection at the starter relay (With a fusible link at the relay for the alternator wire),
AND THEN pick up power for the fuel injection at the starter relay battery cable connection.
That way, the fuel injection computer "SEES" full battery voltage all the time and cycling of injectors doesn't create an issue with the 'Sample' the alternator sees.
When injectors cycle, they case high/low voltage issues, and that will cause the alternator to cause 'Brown Outs' and Voltage Spikes.
When connected to the battery cable, the LARGE SUPPLY FROM THE BATTERY buffers those cycling issues and you have a lot less issues with the fuel injection and charging system.
Q3: solenoid has alt cable, and wiring harness on one end, then blue wire from harness on next terminal, then nothing, then black wire to starter. Correct? What is blank post for?
There are usually 4 posts,
1. Battery Cable
2. Starter Cable
3. 'S' or 'Start' terminal, the terminal that activates the relay to crank the starter,
4. 'I' or 'Ignition' terminal, and it was orignally there to power up the ignition while cranking.
Depending on how/where the 'I' terminal is wired, it was there to supply the ignition with power during cranking.
On some systems, it actually supplied full battery voltage to the ignition to get the engine running when cold and hard to fire...
Some fuel injection systems use it as a 'Cranking Trigger' signal to let the fuel injection know it's time for extra fuel ('Choke') when you first try to start.
In your case, since you don't report hard starting or long cranking times, it's probably not needed.
Q4: there is an extra module of wires that runs from efi relay and battery direct but just has unhooked wires. Is this the correct way to wire it?
No one can answer that without knowing what fuel injection you have and a picture or diagram of what you are talking about,
So if someone *Tries* to tell you different, I'd take that advise with a grain of salt or two...
If these are correct I can start tracing the drain and the light flickering issue ( would this have to do with heat since only occurs around town after 30 min)...
I've seen what you describe before, and it's *PROBABLY* two different issues...
I'd start with making sure the bulkhead connector is clean and tight,
I'd start with making sure the dimmer switch is working correctly and not corroded,
I'd start with checking to see if it's the breaker in the switch that is cycling, or some other part of the headlight wiring/lights are causing issues...
Something no one ever discusses about fuel injection...
IT'S VERY VOLTAGE SENSITIVE!
Everyone *THINKS* that companies went back to the drawing board on alternators because they wanted more power at lower RPM...
That isn't true...
The 'Redesign' and large changes were mostly in voltage REGULATORS & RECTIFIERS, not the basic design of the alternator.
Fuel injection & ultra sensitive ignition modules came along, and there were all kinds of problems with the older alternators killing both sensitive components.
You don't have HUGE electrical loads with a CJ, so you don't need a huge output alternator like most guys think,
But you DO NEED ONE THAT WILL PUT CURRENT OUT THAT DOESN'T ADVERSELY AFFECT THE MORE SENSITIVE ELECTRONICS.
In particular, the OLDER GM SI series alternators had voltage spikes when they first started charging that played havoc with sensitive electronics.
If you have a GM alternator, it's best to use a CS series rather than an SI series...
Until you do some tracking of the issues on there own, there isn't much we can do from here...