Hi Steve. It seems I've done nothing but mess with cruise for months now, so you got to the right guy. I am running cruise on my 91 245 which I installed. There is no relay, per se. The complete system for the 5 speed is two pedal switches (one clutch, one brake), the vacuum diaphram (mounted above and to the rear of the pedal on a big bracket), the ECU (electronic control unit, mounted above the bracket and best accessed by removing the instrument cluster), the vacuum pump (in the engine compartment, above the brake booster), the turn signal/cruise stalk and the wiring harnes. For the 91, the harness is integrated into the car, so this is plug 'n play. Here's what I recommend:

Everything that follows is based on the fact that your cruise was once operating normally. If not, it may have been installed incorrectly and the power wiring may be wrong. (later)

First, check for power at the fuse. Should be connected to fuse #1, but check the fuse panel cover to be sure. Second, take a quick look and make sure the vacuum hoses are routed correctly. Line comes from the vacuum pump (small orifice, not the large one) to the first pedal switch(clutch), then a T to take vacuum to the second switch (brake), then T to the vacuum diaphram. If hoses are in place, disconnect the hose at the vacuum pump (the one that runs through the firewall). Suck on it, blow into it or use a vacuum pump. You'll be able to tell if there is a leak. If so, fix it (obviously). Next step, get a VOM and check that both of the pedal switches are closed with the pedals at rest. That is you should be able to pull off the little white plugs and find continuity at the terminals. Pedal switches are closed when at rest, open when tromped upon.

Next step is to jump 12 volts to the vacuum pump and make certain it is working. Remove the plug at the pump. There are three terminals on the pump itself. You can't really hurt the thing. Two combinations of terminals and hot/ground leads will run the pump. If so, you are good there. Make sure it actually sucks. Get it running and see if the vacuum diaphram pulls the gas pedal down. Make sure you have vacuum all along the route. Stepping on either pedal will release the vacuum if the switches are working correctly.

For 91, there is no lead to be checked on the back of the speedometer, as the wiring is internal and in the harness. If you have checked all of the above and don't have operation, get back to me. You'll need to do some more involved checks to determine which part has failed or if power has failed. I can tell you this: The ECU's are much more durable than one would think. I have spares, for nothing. Never had one go bad on me yet. Stalk switches are more prone to failure, but the problem is usually in the wiring or pedal switches.

One more thing you can do: The cruise circuit uses a supervisory voltage through the brake lights to maintain ground for the ECU. If the brake lights are experiencing any sort of failure that involves the "bulb out" relay, the cruise will not pull in. Make certain of the following:

1. Remove one of your brake lights and make sure your bulb failure relay works. With one bulb out, hit the brakes. Bulb failure light means that circuit of the bulb failure relay is good. If not, change it. Check cruise.
2. Make certain both brake light bulbs are identical.
3. Use an eraser to make sure the contacts on the bulb holders and on the tail light circuit overlays are clean and making good contact.
4. Each tail light has a ground wire screwed to the sheetmetal near the light (inside the plastic cover doors in the trunk). Make sure the grounds are clean and secure.

As the owner of two 5-speed 245's, one '91 and one '88, I can attest to the fact that the upshipt indicator system can be a problem for these cars. It utilizes the clutch switch, sharing the ground circuit with the cruise. As noted, if you don't find the problem with what's here, contact me at dpsam@sbcglobal.net, I'll be happy to talk you through the rest of the troubleshoot. We'll get ya goin'!

[Thanks to "Lucid" and others for past help with cruise!]

Happy new year.

Dave