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Grounds and general wiring.

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Two years ago I replaced my fuel pump with a Bosch. At the time I complained that the pump was slow to respond and remained sluggish, I referred to the pump as a POS. Pump would slowly prime to 14lbs but when throttle was applied it would dip down to 10-12lbs. 

 

Cab forward, I have gone through most if not all the wiring-

Head light harness

C101 delete. 

New cables, new grounds. 

Eliminated all unnecessary wiring. 

Aftermarket ignition switch.

New fuse block. 

New alt, new starter, new ignition module (NOS).........etc..etc....etc.............

Still have more to do, aftermarket gauges, existing gauge wiring will be modified or removed. Still have to wire the amp and so forth. 

 

 

The only wiring that I have not gotten to was the rear, tail lights and fuel pump. Bed is coming off for paint, new tail lights, and I will rewire for trailer brakes/lights and peekaboo back up lights. 

 

Back to the fuel pump-

Last weekend, after reading of some of the complaints here, I decided to remove the taillight and look at the G107, I've been aware of it, just never bothered. 

 

Here-

kNmP2jO.jpg

 

Not only was there common corrosion around the sheet metal screw (no rust) but as you can see the corrosion runs deep into the wire.

 

 

I ran a new ground temporarily to a ground post at the rear. 

Pump now primes immediately and will hold 17lbs regardless of throttle. Pump is now running as it should. 

 

More here-

QeWzYQS.jpg

 

Anecdotal? No, Jeep wiring is notoriously for $#!&. 

 

Why my post?

Currently, page one-

 

No start.

Strange blinker.

Battery overheats.

Radio pops. 

No back up lights.

Wiper speeds.

No spark.

Horn relay. 

 

Same questions, same causes, same answers. 

 

If you have not gone completely through your wiring, you need to. If you are not comfortable, take it one wire at a time. But look at the big picture, otherwise, you'll spend all your time chasing one problem after another. 

 

 

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1 hour ago, Jeep Driver said:

Two years ago I replaced my fuel pump with a Bosch. At the time I complained that the pump was slow to respond and remained sluggish, I referred to the pump as a POS. Pump would slowly prime to 14lbs but when throttle was applied it would dip down to 10-12lbs. 

 

Cab forward, I have gone through most if not all the wiring-

Head light harness

C101 delete. 

New cables, new grounds. 

Eliminated all unnecessary wiring. 

Aftermarket ignition switch.

New fuse block. 

New alt, new starter, new ignition module (NOS).........etc..etc....etc.............

Still have more to do, aftermarket gauges, existing gauge wiring will be modified or removed. Still have to wire the amp and so forth. 

 

 

The only wiring that I have not gotten to was the rear, tail lights and fuel pump. Bed is coming off for paint, new tail lights, and I will rewire for trailer brakes/lights and peekaboo back up lights. 

 

Back to the fuel pump-

Last weekend, after reading of some of the complaints here, I decided to remove the taillight and look at the G107, I've been aware of it, just never bothered. 

 

Here-

kNmP2jO.jpg

 

Not only was there common corrosion around the sheet metal screw (no rust) but as you can see the corrosion runs deep into the wire.

 

 

I ran a new ground temporarily to a ground post at the rear. 

Pump now primes immediately and will hold 17lbs regardless of throttle. Pump is now running as it should. 

 

More here-

QeWzYQS.jpg

 

Anecdotal? No, Jeep wiring is notoriously for $#!&. 

 

Why my post?

Currently, page one-

 

No start.

Strange blinker.

Battery overheats.

Radio pops. 

No back up lights.

Wiper speeds.

No spark.

Horn relay. 

 

Same questions, same causes, same answers. 

 

If you have not gone completely through your wiring, you need to. If you are not comfortable, take it one wire at a time. But look at the big picture, otherwise, you'll spend all your time chasing one problem after another. 

 

 

Let's go a step further.....

 

The fuel pump and fuel tank sending unit ground at a sheet metal screw up behind the spare tire on an XJ, and behind the driver’s taillamp on an MJ.

Not only is a sheet metal screw a lousy way to ground things, this ground path is long and travels through some connectors that are prone to corrosion and moisture.

Locate the black wire on  the HARNESS side of the fuel pump/sender 3 wire connector. Remove a 6″ length of the split loom covering. Strip back about 1/2″ of insulation from the BLACK wire.1-fuel pump ground MJ

Take your new ground wire, preferably at least 14 gauge and 12 to 18 inches long as needed, strip it about 3/4″, and wrap it around the exposed part of the harness plug wire.1-fuel pump ground mj-002Solder the connection. Tape it up and reinstall the split loom covering.1-fuel pump ground mj-003

At the other end of your new ground wire, add a crimp on eyelet. Attach the eyelet under a bolt that goes directly into the chassis. Be sure to clean the attaching point til shiny and apply OxGard to the contact surfaces.1-fuel pump ground mj-004

Revised 1-31-2016

 

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This is a good one to do, along with the blower motor and wiper ground upgrade.

 

The ground point for the complete instrument cluster on your XJ or MJ is located up under the driver’s side dash. If you lay on your back and look up under there with a flashlight, without wearing a hat, you will see a black wire attached to a shiny piece of metal almost directly above the hood release knob. The screw will have either a ¼” or 5/16″ head on it.

This ground point is responsible for handling the ground circuit for the following items: Dome lamps, seat belt and key warnings, transmission power/comfort switch, wiper switch, headlamp switch and delay module, fog lamp switch, cargo lamp switch, all instrument panel grounds and illumination, power windows and door locks, cruise control dump valve, and a few more things.

The problem is that where the ground point is located does not share good contact with the chassis where the ground should be. The solution is simple:

  • Make up a jumper wire with #10 gauge wire about 10″ long. On one end, crimp on a ¼” round wire terminal. On the other end, crimp on a 3/8″ round wire terminal.
  •  
  • Remove the screw from the existing ground wire and attach the small terminal of your jumper so that the original wire and your new jumper share the same attaching point, one over the other.
  •  
  • Look above the driver’s side plastic kick panel just forward of the top of the hood release knob. You will see an 8mm stud there. Attach the large terminal end there with a washer and nut over it tightened securely. Use a coating of OxGard at all ground contact surfaces when attaching the screw and nut.

IP ground location

**Special note for Comanche owners: Make your jumper wire 12″ long and attach it on the driver’s side kick panel close to the fusebox on the 8mm stud.**

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On 87 to 90 MJs and XJs, the blower motor’s factory grounding point is on the driver side inner fender under the sheet metal screw. This ground is shared with windshield wipers, front windshield washers, rear windshield washers, AC clutch relay, fan control relay, fog lamps, fan motor, headlamps, front turn signals, front side markers, and park lamps.

So your blower motor has its ground point 10 feet away from where it is located!!

What we’re going to do is leave that ground intact and also ground the blower motor on the passenger side inner fender much closer to the blower motor itself. This will also benefit the other components on the factory ground circuit. Take this opportunity to refresh the factory ground as a matter of course. Remove the screw, scrape the surface to bare metal and reinstall the screw securely.

Here’s what I do to get the ground much closer to the blower motor and add another ground point to this overloaded ground circuit.

Find the blower motor connector on the passenger side. Red and Black two wire connector.

Find a location where the black wire can be made to reach the passenger side inner fender, and cut the wire. You may have to do some rerouting of the harness to achieve this.

Take both cut pieces of wire and put them together into a yellow eyelet and crimp. Fasten the eyelet to a place on the passenger side inner fender with a sheet metal screw after applying OxGard to the contact surfaces. Be sure to scrape the attaching point on the fender to bare metal first.

Your blower motor will now turn faster and last longer, and the other electrical components on the circuit will benefit from a better ground path.Blower motor factory ground Blower motor new ground

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Here's the current Tip content at www.cruiser54.com

 

There are also a bunch of links on the home page. 

 

INDEX

Renix tool kit 2

Cruiser’s Mostly Renix Tips

Technical DIY instructions covering common issues on the Renix XJ Cherokees and MJ Comanches (1987-1990). Preventative and proactive procedures to save you headaches, time, and money.

Many of these tips were provided to me and my buddy Joe by JeepTech when I was Service Manager/Shop Foreman at a Jeep dealer from 1980 through 1992. That’s what “The Book” is all about. Our notes from back in the day. Right from the Field Service engineers. Thanks Lonnie and Big Al!!  Most were never published, until now.

Tips 1 through 5 are a great place to begin before chasing your tail with parts replacements on your 87 and 88 Jeeps.  These are pretty much “haftas” in Renix Jeep ownership. You can skip Tip 2 if you have an 89 or 90. But, do the Tips first……….Avoid firing the “parts cannon” at your Jeep!!!!!!!parts cannon 2

 

The next priorities are Tips 11, 13, 31, 25 and 26

A simple multimeter is handy along with a few other basic tools……so dive in and get to know your Renix Jeep.

Some Tips also transfer to later years, or the techniques can be adapted.

 

1 – Ground refreshing

2 – C101 connector refreshing

3 – Connector and relay/receptacle refreshing

4 – Coil/ICM contacts

5 – Checking sensor grounds

6 – Sensor ground upgrade

7 – CPS testing and adjusting

8 – TPS testing and adjusting

9 – ECU connector refreshing

10 – Trans plug connector refreshing

11 – Throttle body and IAC cleaning

12 – Setting your 4.0 to #1 TDC

13 – Renix Distributor indexing

14 – Restoring Throttle Butterfly Adjustment

15 – Rear main seal diagnosis

16 – Vacuum test for exhaust restriction

17 – HO engine into Renix

18 – Improving the instrument panel ground

19 – Headlight harness installation

20 – 4WD shifting tips

21 – Renix EGR valve test

22 – Renix vacuum harnesses

23 – CPS timing advance mod

24 – 4.0 Engine date codes

25 – Valve cover mod ***NOW WITH VIDEO***

26 – Oil Filler cap Mod

27 – C101 Connector Elimination ***NOW WITH VIDEO***

28-Improving blower motor performance

29-Improving the fuel pump ground

30-Adding the Sentinel Headlamp feature

31-Throttle body to MAP hose upgrade

32-Renix metric oil filter to SAE filter

33-Converting to an open cooling system

34-Eliminating the Heater Control Valve

35-Reducing cabin wind noise

36-Bypassing the Power/Comfort switch

37-Best injectors for Renix

38-Improving the wiper motor ground

39-4.0 Engine Removal

40-More power for your 87 and 88 4.0 ***VIDEO***

 

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Amc harnesses for the engine and the one that runs along the firewall, then past the battery, and out & travels across the front crossmember and back into drivers side and connects to the firewall has probably anywhere from 15-20 $#!&ty crimps & wrapped with duct tape without any insulation and are prone to corrosion. 

 

I had to search through those harnesses and soldered every joint I come across. 

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