Strange problem with 87 Trooper

truchas · #1 11-20-2004, 08:12 AM

I've been having this problem with my Trooper for a while now and can't figure it out. When its cold, the engine starts fine but in a few minutes after it starts to warm three warning lights come on, I believe they are the "check battery, low gas, and brake". When this happens the idle speed is affected and the truck stalls at stop lights, etc. However it will start again and stay running as long as i give it gas. After maybe 5-10 minutes (when it gets fully warmed up) the warning lights suddenly go out with an audible click and the idle is ok. I did change out one of the relays in the fuse box but it didn't help. I'm thinking that since this problem is temperature related it may be a temp sensor, but don't know..... Any ideas? TIA Chris

sunnyjim630 · #2 11-29-2004, 08:57 PM

I'm hoping that you figure it out or somebody gives you a lead.
My friend has an 86 Trooper with a 2.3l that does almost the same thing.
It is an intermittant problem. The battery, low gas, and brake lights go on, the heater won't work and the engine at idle revs to 3000. I looked at the schematics in the manual and they seem to point to a "mode switch". I haven't found it yet. Know where it is? Good luck! If I find out anything I'll drop a line.

SunnyJim

Quote:

Originally Posted by truchas

I've been having this problem with my Trooper for a while now and can't figure it out. When its cold, the engine starts fine but in a few minutes after it starts to warm three warning lights come on, I believe they are the "check battery, low gas, and brake". When this happens the idle speed is affected and the truck stalls at stop lights, etc. However it will start again and stay running as long as i give it gas. After maybe 5-10 minutes (when it gets fully warmed up) the warning lights suddenly go out with an audible click and the idle is ok. I did change out one of the relays in the fuse box but it didn't help. I'm thinking that since this problem is temperature related it may be a temp sensor, but don't know..... Any ideas? TIA Chris

travelman · #3 11-30-2004, 09:55 AM

I'm guessing the problem may be a dying alternator. The engine and fuel pump start off the battery. After 30seconds or so it switches over to the alternator. If the alternator isn't putting out enough volts you can get some weird running and flashing light symptoms. After a few minutes of running, the alternator warms up, starts working properly, and the symptoms disappear.

I am not saying this is guaranteed to be your problem, but it is a relatively simple possibility to check out. Put a volt meter on it and watch the readings as the engine goes from cold to warm to hot.

As to a temperature sensor problem, I kind of doubt it. Those tend to throw a code of some sort when the computer doesn't sense that the engine has warmed up in the proper time. Then again I have a newer trooper with more electronics on it so maybe I am way off-base.

truchas · #4 11-30-2004, 06:18 PM

Appreciate the input. The strange thing now is that my Trooper hasn't done it since the day I posted!! It has been an intermittent problem, but frequent until the last few days. Symptoms exactly what you described Sunnyjim (I forgot to list one of the symptoms being that the heater blower won't go on when the warning lights are on). Will see if I can find the "mode switch", and also will check the alternator per Travelman's suggestion. It has been doing this a long time though, seems like the alternator would have died by now...... Thanks.

sunnyjim630 · #5 12-16-2004, 10:29 PM

Did you find your problem yet?

soundrew · #6 12-22-2004, 08:54 PM

I have a similar, but less severe, experience. I occaisionally get a number of warning lights coming on and, perhaps related-- perhaps not, the engine idle occaisionally revs up and down. The notion of an alternator failure in the making seems plausible but I also think it might be a bad chassis ground (which I'll check when we get some warmer weather). Just follow the negative battery terminal and make sure there is a clean connection at the other end. I had a situation like this with my dodge van-- instruments went wacky and it would occaisionally stall. It was a bad ground and once I replaced the ground lead and cleaned and tightened the connection, everything has been OK since.

sunnyjim630 · #7 01-15-2005, 01:40 PM

My friend's Trooper has stopped acting up. Do these things go through some kind of menopause?

truchas · #8 01-31-2005, 12:25 PM

I started checking the voltage at the battery when the problem was happening (12.5 volts) and when it wasn't (14.5 volts). This made me think it was the alternator. I put in a new one and haven't had the problem since. Also my trooper idles a lot better cold or hot. Thanks all for your input, looks like Travelman called it right.

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