FOR SALE!

100 bhp per Litre







Updated:
24 April 2007

Getting Wired

In this project, I did not have the benefit of a donor Turbo van, so it was essential to get the Factory Service Manual for a 1990 (SBEC) Minivan. I already had the 1993 Minivan FSM. The wiring diagrams for both the target (1993) and donor (1990) cars are absolutely essential, DON'T attempt a conversion without them.

Next, a complete under-hood donor harness from a 1990 - 1991 Turbo I vehicle was sought and obtained. It really doesn't matter if it comes from a Minivan, but it must be SBEC (90-up) vintage, as the all important injector harness is wired sequentially (not batch, as 89-and-older turbo's were). You basically want the harness for the seven unique, turbo-specific sub-harness connectors listed here.

The vehicle harness was then completely removed and laid out against the donor harness for visual comparison against the FSM wiring diagrams. In this conversion, it makes more sense to modify the target vehicle's existing harness (there's no going back to TBI!), rather than to try and use and modify the 1990 Turbo donor harness. (It's possible to make the changes with the harness left in the vehicle, but I like doing the changes with the harness on a bench in the shop.

On the bench, all the under-hood crud and dirt can be completely removed, all split-loom, insulation tape and connectors can be inspected, cleaned and de-oxidized. To avoid potentially unreliable splicing, Standard Motor Products, Inc's., P/N CG52 terminals were used for inserting the seven new turbo-specific circuits into the vehicle's existing 60-way SBEC vehicle harness plug. 

To Prevent Electrical Wiring/Connector Problems follow this procedure:

Use a good spray cleaner like DeoxIT D5 Connector & Contact Treatment. This breaks up the oxides and contamination. This is only a cleaner and the cleaning improves conductivity. Avoid Silicone-based cleaners. Use a Di-electric grease only to seal or lubricate non-conductive connector isulation surfaces.

Use an electrical contact enhancer like Stabilant 22 or Stabilant 22A.  Initially it is non-conductive and then switches to a conductor in the presence of electricity. This switching ability is set so that the material will remain non-conductive between adjacent contacts in a multiple connector, and yet enhance the conductivity of each connector.  It's as if it had its own brain, and it provides a tenfold to a hundredfold increase in connector reliability.

Note: Skip this paragraph if you're not technically oriented. Stabilant 22 is a potentially electrically-active material which through a synergistic combination of effects enhances conductivity within a contact without causing leakage between adjacent contacts. While Stabilant 22 has a high dielectric constant it acts to form a capacitive layer which is in parallel with whatever residual resistance exists in the contact increasing the passage of AC signals. However, given sufficient DC bias within the gaps of the contact the thin film of Stabilant 22 will "switch" to conducting by quantum tunneling and thus limit the resistance of the contact to a serviceable level.

Here are some suggested uses for Stabilant 22:

Fuses

The stabilant will reduce the possibility of fuse contact heating which can cause a fuse to blow below its rated current on a circuit that is really O.K. While the new blade type fuses are more reliable than the older 3AG/AGC types they still need help. 

Lights

Poor contacts in the lighting connectors will result in a voltage drop at the connector that robs the lights of some of their brightness. Use the Stabilant when replacing bulbs.

Sensors

Often a "sensor malfunction" error message on a diagnostic computer appears because of a faulty connection to the sensor.  Many times you can buy a new sensor only to have the same error message re-occur hours, days or even weeks later. The difficulty is that quite often the problem is the connector itself rather than the sensor. Replacing the sensor "cured" the problem only because the vary act of replacement simply "wiped" the connector.  Using a drop on the connector may save the cost of a sensor.

Instrument Clusters

Malfunctioning lights or instruments are often caused by poor contacts. I once had an intermittent speedometer that was the result of poor connections in the instrument cluster.

Other items

Battery terminals, door activated switches, voltage regulators on alternators, and plug-in relays are other areas that can be helped by use of a contact enhancer.

However, one word of caution is needed.  Do not use a contact enhancer such as Stabilant 22 on a switch for an inductive load. In other words if the switch sparks when disconnection occurs do not use the stabilant as it would increase the sparking. (However it is O.K. to use it on the wiring harness connections for these switches and circuits.)

DeoxIT D5

Craig Laboratories, Inc.
16744 West Bernardo Drive
San Diego, CA 92127-1904

Phone:(619) 451-1799
FAX: (619) 451-2799

Stabilant 22

D. W. Electrochemicals Ltd.
97 Newkirk Road North, Unit 3
Richmond Hill, Ontario L4C 3G4
CANADA

Phone:(905) 508-7500
FAX:(905) 508-7502

Finally, the harness can more easily be electrically verified and tested before placing it back in the vehicle. 

If you've never done wiring work before, it's best to seek out a harness maker, preferably one that has experience with automotive electrical harness repair or construction. You'll need to make a very detailed change plan or drawing (also handy for future troubleshooting), again referring to your FSM's electrical diagrams and connector tables. But by using a harness maker, you'll get back a harness that's better than the one that came new in your car, but is now tailored-made to your vehicle's unique requirements.

In my case, I used Specialized Manufacturing, of Draper, Utah. Bob Simons and his crew (thanks Taggert!) did a great job!

When your wiring is ready to go back in the vehicle you'll need a 1990 - 1991 SBEC from a Turbo I (auto or manual, it simply doesn't matter, other than the auto's have a de-acceleration "1500 rpm-hold" curve down to about 2 mph

Again, I was very fortunate, as my 1990 Turbo I SBEC  came from long-time Mopar turbo-guru Thomas "Gus" Mahon, last summer before his untimely passing. Call it spooky, but there's a little "Spirit of Gus" riding up front, inside my Turbo van.