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39 Posts
Discussion Starter · #1 ·
Hey all!
I'm still stuck after days of troubleshooting and hours and hours of searching...

I added some coolant to my overflow tank, (a touch too much in hindsight) and after about 40 miles of driving, my speedometer started cutting out on the freeway... I got a transmission code 4 (Speed sensor) but no CEL. Seeing as mine was the original sensor (164,000 miles) I figured the old one was worn and tired. Ordered the new part, installed it, and it worked great for a day or two, then the problem reappeared... Upon further investigation, I noticed a small amount of coolant is coming down the speed sensor wire/harness (from a location unknown). It's not much, but enough to wet the wire connector, and leave just a bit of coolant on the top of the sensor.

I have...
Replaced the speed sensor
Checked coolant level
Cleaned the contacts on the Speed sensor connector (Several times)
Swapped out the dash cluster with my Girlfriends Odyssey to eliminate the possibility of a bad speedo cluster (of Accord fame).

The speed sensor works fine, until the van warms up, and that tiny bit of coolant finds it's way into the connector. Once there's coolant/resistance, the speedo reads way low, and if' i'm on the freeway, the torque converter won't lock up ( i.e. engine just screams).

Where could this coolant be coming from?
The Tstat housing is clean, and does not appear to be leaking...
Could it be a bypass hose/ heater core issue?
There is NOTHING obviously leaking around the speed sensor. The coolant is following the speed sensor leads (back into no-man's land).
Is there a freeze plug or something like that back there?

Thanks again!
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