Fuse Box Take-a-Part

92 SL DOHC

 

You have to wrestle with the wiring harness to get a wrench on the connectors,

We were getting sketchy readings on the injector supply voltage,

The connector on the right was showing some oxidation which was probably the reason.

All the spider webs and Arthropoda were evicted,

 

4 bolts hold the sub frame in,

 

If you ever wondered what all those A3 and F4 type numbers you see along the borders of the UHJB as seen the Service Manual schematics...

Numbers that you see in the service manual correspond to these numbers stamped on the connector body.

But all three use the same numbers,

If you want to check continuity, which connector do you stick your meter on?

Well it turns out that if you want to check your injector voltage connectors that there is only one connector cavity with the spade lug that matches the schematic in the service manual.

 

In order to take apart the junction box, you must remove all the stainless steel lugs that serve to connect the circuit tabs to the Mini and Maxi fuses and the the relays.

There are quite a few of them, they are connected to unused fuse tabs also.

There are three sizes, small for tghe mini fuses, medium for the Horn, AC, and other big relays, and large for the main buss Maxi 30 A fuses.

 

Try as you may, you will not find these connectors anywhere online.

There are stainless, so they are pretty tough and respond well to re-tensioning.

It took a lot of pressure to press the fuses back in after all the lugs were re-tensioned.

I did this by pressing on the two curved parts of the lug with a small pair of needle nose pliers.

 

Once all the conns are pulled and the sub frame removed, the circuit plates can be removed.

There are six of them that are held together by the crimped brass inserts.

 

You can persuade the edge of the inserts upward with a screwdriver. Then a pair of small diagonal cutters can be used to finish the job.

The top insulating plate has been removed, here is circuit #1

>

 

here are all the circuit plates in order>

 

All the layeres were inspected for damage and sprayed down with DeOxit and restacked.

Everything looked good, no signs of heat damage or corrosion, all those circuit traces are stainless.

The brass inserts were re-crimped as best as possible with a stepper drill and a tack hammer.

The under hood junction box is back in the car and the voltage to the injectors looks good.

My LED battery voltage meter that feeds off the radio link also showed signs of improvement with the voltage now reading 12.6 instead of 11.9.

There is a plastic tray in which the junction box sits. Having moisture in this tray is not good for all those connections. Maybe pop that junction box out of the tray once in a while to have a look. And avoid pressure washing your engine.