Dear Art Benstein,

Hope you're well. If I recall correctly, when a speedometer ceases to send a speed signal to the cruise control computer, the cruise control will not engage.

What is the speedometer component, failure of which causes the speed signal to be lost? Is this component replaceable, or is the entire speedometer "kaput"?

My speedometer works correctly, except that it does not send a speed signal to the cruise control computer.

I read through the FAQs on speedometer repair, but saw nothing that pointed (pun intended) to a repair that restores the speedometer's capacity to send a signal to the cruise control computer.

Thanks in advance for the benefit of your insights!

Yours faithfully,

Spook

Hi Spook,

I'm gonna mark this thread with the pulldown for 1993 year. Please change it if that is not the correct topic.

The output which operates the fuel computer idle control and cruise control is combined in the speedometer at pin 2 on the gauge connector. I am aware of this only because you provided the example unit for me to repair and document.

Logic would have it, if the fuel computer was not setting a 311 DTC, a cruise fault would not originate in the gauge, but if related to that signal being missing, would lie in some external wiring on or around the instrument cluster.

I vaguely recall someone making a detailed post here on BB showing some loose pin or broken trace they repaired to get this signal beyond the gauge itself and to the cruise computer. A mechanical problem with an electrical wire. I'd have no knowledge of that myself, having no 900 model Volvos to worry about.

To answer your query, I pulled up the page http://cleanflametrap.com/speedo7.html which toward the middle begins a series of pictures of the repair of the unit you sent me some time ago. Scroll to "1993 Speedometer."

I hope this helps you, and I always enjoy hearing your on-line civility expressed on this forum.


--
Art Benstein near Baltimore

GREAT TRUTHS THAT LITTLE CHILDREN HAVE LEARNED:
No matter how hard you try, you can't baptize cats.

They do that, get all auld and lose seal and the electrolyte inside or, when connected to a variac, as you turn it up, are dried out and go pop in that auld vacuum tube or early solid state sort of equipment.

Excellent images!
--
Give your brickboard.com a big thumbs up! Way up! - Roger Ebert.

Dear Art Benstein,

Hope you're well. I finally got around to swapping-in a known-good cluster, with less than 38K miles on it. It made no difference. I reasonably infer that the problem is not in the speedomete or the cluster's circuit card.

I also read carefully the Volvo wiring diagrams as concern cruise control. There's only one wire from the speedometer to the cruise control module. It is an orange-green wire, that connects at a two-contact male spade-type connector at the center of the cluster's circuit card.

This dual contact - with a shiny brass-colored cadmium plating - is secured to the circuit card by a single Philips-head screw. I removed the contact and cleaned it using DeoxIT and an abrasive pad. I also cleaned the wiring harness contact with DeoxIT.

I'll re-test. If the problem persists, I'll make a connector straight from the back of the cluster to the Cruise Control Module (hard to access). If that doesn't restore cruise control to operation, then I'm at a dead end.

Thanks again for your suggestions.

Yours faithfully,

Spook

Dear Art Benstein,

Hope you're well. Thank you, for the guidance that the problem is more likely in the wiring than in the speedometer itself.

I'll swap-in a "known-good" instrument cluster and see if that unit provides the signal to the cruise control computer. If not, then I'll have to look at the wiring.

Thanks again for your help!

Yours faithfully,

Spook

Steve Ringlee has experienced this. I believe he replaced the entire speedometer. Maybe he will reply here.
--
john