cluosborne

I just finished replacing the battery cables on my 1988 GTU. If you're not relocating the battery and just plan to keep the battery in its stock location, there are some things you need to know before you start.

First, you'll want to buy a set of aftermarket cables. The stock ones are part of a section of the car's wiring harness so OEM would cost an arm and a leg. You'll have to disconnect almost every connector along the cables from the fuse box to the starter motor and unwrap it to separate the cables. Oh, and you'll have to remove the starter to replace the ground cable.

In regard to the 80AMP fuse, one of the wires runs from the lead battery cable to the fuse box; it ends in a ring terminal. If you follow the original lead cable and unwrap it (you're going to do a lot of unwrapping to separate the old cables from the harness) you'll come across a crimp that attaches two wires (one that ends in the ring terminal, another in a black clip). You can cut that part of the wire and reuse it with the new cable.

The other ring terminal that leads from the 80AMP fuse does NOT go to the starter. I made the mistake of thinking that and cut that wire, so I had to reconnect it. If that happens, you can get an 8-gauge set-screw inline coupler from Radio Shack that'll do the job, just strip off the insultation, insert the wire, tighten the screws and cover with electrical tape. So DO NOT any wires that lead AWAY from the fuse box, only incoming from the battery cable.

I used electrolytic grease on all the connectors, and the battery terminals. The battery was replaced with an Optima Red top. After everything was reinstalled and connected, the engine started on the first try. The starter didn't sound worn out (the old cable clamps were horribly hammered-literally, they wouldn't fit the battery terminals snugly) and there was plenty of juice.

cluosborne

Update: I strongly suggest that you make sure to mark anything you disconnect. I found that my oil pressure gauge was no longer working and though the wiring diagram shows a connection to the unit itself, I have seen differently in my engine compartment.

Ok, and I did ask about this in a separate post. According to the FSM wiring diagram, the connection to the oil pressure gauge is run to a 6-pin connector, which then branches off to two connectors: one connects to the oil pressure sender, the other to a grounding capacitor called a "Condenser."

While I was disconnecting the harness so that I could unwrap the old cables, I am sure that I didn't disconnect anything from the oil pressure sending unit (which is located under the oil filter right?). The condensor is where it's supposed to be, and the connnector is there too (it's tapped onto that wire and wrapped in electrical tape), but instead of the wire ending in another connector for the oil pressure unit, it extends down under the car along the transmission. It is a yellow wire with a red stripe.

Am I in an another universe where my FSM was written differently, or did someone modify the wiring?

saltlakebay

On the s4 that second "condensor" connection for the oil pressure sender is found in one of two places. On my car (as it shows in the FSM), its underneath the trailing coil pack. Has that ring connector with the little tiny black box.

I've also seen engine pics where its connected to a slave cylinder bolt.

I hope thats what you were asking. And.. yes, the oil pressure sender is that retarded bell looking thing under the filter area. The connector is a clip kind that just slides on.

cluosborne

Yep, the condensor was bolted to the slave cylinder bolt. But, I can't find that clip on connector. I followed that wire and didn't find another connector. It's just weird.

I'm going to go under the car and trace that wire. If it connects to nothing, I'm going to remove it and redo that part of the wiring so that I won't get into a hissy fit next time.

Icemark

I don't get what you mean... The yellow/red from the condensor ties into the yellow/red from the oil pressure gauge, then it goes to pin 6 of FE-02 plug and then from there goes into the main front harness and in through the firewall to the cluster.

Could you be confusing it with anotehr wire...

or maybe you have a 87, which used different plug layouts and connections?

cluosborne

No Icemark, I'm not. it's the same wire, yellow with a red stripe, which runs through the same connector, FE-02, and to the condensor, same wire, then runs down under the car.

Oh, the manufacturing date on the car is September 1, 1987. But the car is a GTU. It has the hard suspension, 5-lug wheels, 4-pot calipers, and the aero pieces with the GTU rear spoiler (I had removed the aero pieces because they had rusted out). The only option it seemed to have was the sunroof. It didn't have cruise control (I added it less than a month after I got the car), power locks or windows.

If it was manufactured in 1987, does that make the car a 1987 instead of an 1988?

Regardless, with the exception of this one wire, from what I could tell in the wiring diagrams and what I've seen when I've worked on the car's electrical system, everything seems to be what is in the FSM.

Icemark

No that is an 88, The 87 had a connector at the condensor itself, I thought maybe you were mixing that up.

cluosborne

It's good that you're challenging my thinking and asking questions.

It's definitely the same wire; I hooked that wire directly to ground and my oil pressure gauge shot right up. Presently, I have it disconnected until I trace the wire under the car and find out where it physically leads.

Odd, maybe the connector for the sender got lost or god knows what.

cluosborne

Well, turns out that I'm an idiot sometimes. Yesterday, I realized that one of the connectors was not for the condenser, but actually for the sender. So, it's connected and I'm getting a reading.

Now, as for where the wire goes. I changed the oil today, and as it turns out the wire does not run down under the car. It actually goes down to the starter and curves back UP and terminates in the correct connector. Because the connector is black, and seems to be down low, I never saw it. Who in their right mind designs a wiring harness that dips down and back up?

Anyway, I ripped off the old black wrapping, wiped off the wires, and covered, routed, and rewraped the harness, with the wire and its connector up where it belongs, ready for its new condenser.

So, Icemark, and everyone else who responded, you were right and I was blind not to see it until now.